Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Accurate characterization of foot type can facilitate identification of patients at risk for different foot disorders and direct operative treatment. Foot type can be determined qualitatively with visual assessment and quantitatively using arch index (AI), calcaneal pitch (CP), Meary's angle (MA), and foot posture index (FPI). Agreement between various foot typing measures is unclear. The purpose of this study was to assess the agreement between different measurements of foot type. We hypothesized that quantitative measures would have better interrater reliability than qualitative measures, and that visual assessment of foot type would be strongly correlated with radiographic assessment. Methods: Bilateral foot photographs were acquired from 92 asymptomatic participants (50 men, 42 women, mean age of 43.3+- 18.6 years) to assess photographic arch type (PAT) and photographic foot posture (PFP). Hindfoot alignment and lateral radiographs were acquired of each foot to assess calcaneal pitch (CP), Meary's angle (MA), x-ray foot posture (XFP), and x-ray arch type (XAT). Photographs and radiographs were assessed by five reviewers in random order. Foot Posture Index (FPI) was determined through manual exam. Arch Index (AI) was measured on lightbox images. Interrater reliability was assessed using Intraclass Correlation Coefficient (ICC) for continuous variables and Kendall's W for categorical variables. Correlations between measures and sensitivity/specificity were assessed using calcaneal pitch as the reference standard with cavus feet >= 26 degrees and planus feet measuring <= 19 degrees. Results: Interrater reliability of XFP (W=0.522), XAT (W=0.676), PAT (W=0.831), PFP (W=0.612) ranged from strong to extremely strong. Interrater reliability of MA (ICC=0.711) and CP (ICC=0.804) were moderate and good. Correlations between foot arch measurements ranged from low to high (Table 1). Fair correlations were identified between foot posture measurements (r=0.356 to r=0.442). Overall, XAT had the greatest sensitivity and specificity for planus (0.68, 0.93) and normal feet (0.92, 0.62), and the greatest specificity for cavus feet (0.98). AI demonstrated the greatest sensitivity (0.47) for cavus feet. Compared to AI, photographs had superior sensitivity for identifying normal feet (0.73 vs. 0.43), the greatest sensitivity for identifying planus feet (0.54 vs. 0.06), and the greatest specificity for identifying cavus feet (0.95 vs. 0.71). Conclusion: Agreement between methods varied widely, suggesting that classification is dependent upon methodology and cutoff values selected. PAT had the highest interrater reliability, whereas correlation between XAT and PAT was moderate, suggesting that radiographs are needed to accurately assess the longitudinal arch.
Revision total joint arthroplasty (rTJA) is a resource-intensive procedure addressing failed primary total joint hip (total hip arthroplasty [THA]) and knee arthroplasty (total knee arthroplasty [TKA]). Despite predictions of increased demand, reimbursement for rTJA has not kept pace with increasing costs and may be insufficient compared with primary procedures. The study aimed to highlight the diminishing surgeon reimbursement between primary and revision THA (rTHA) and TKA.
Category: Basic Sciences/Biologics Introduction/Purpose: Foot morphology is a key aspect of patient evaluation. Individuals with Pes planus usually have medial foot pain; those with Pes Cavus commonly have pain over lateral foot. Foot Posture Index (FPI) is a qualitative measure that uses six specific physical exam parameters. Arch index (AI) is a quantitative measure in which the footprint is photographed and measured. Radiographs allow for visualization of the bone and used to directly measure parameters of foot morphology such as calcaneal pitch (CP). The purpose of this study was to determine the sensitivity and specificity of surgeon observation, FPI, and AI in determining foot type, with CP serving as the reference standard. Our hypothesis is that surgeon observation will be more sensitive and specific than FPI and AI for identifying foot type. Methods: Following institutional review board approval and informed consent, we examined 41 adults (82 Feet) (average age 37.8+-17.6 yrs.; range: 20 to 68 years old; 20F/21M) without history of prior foot or ankle injury. Subject evaluation included bilateral FPI exam, lateral and hindfoot standing radiographs, pedographs, and weightbearing photographs. Three authors were trained to perform standardized FPI assessments. The radiographs and photographs were presented in a randomized order to a board-certified foot and ankle orthopaedic surgeon to classify a foot as either planus, cavus or normal (Figure 1). Calcaneal pitch was measured for each foot by finding the angle between the inferior surface of the calcaneus and the supporting surface, with normal classified as 18°-32°, planus <18° and, and cavus>32°[2,3]. Arch index was calculated for each foot from pedograph, with normal classified as 0.21 to 0.28, planus < 0.21 and cavus >0.28. Results: The gold standard calcaneal pitch measurements identified 12 planus, 57 normal, and 13 cavus feet. Surgeon observation was the most sensitive for identifying planus feet and most specific for identifying cavus feet (Table 1). Arch index was the most sensitive for identifying cavus feet and most specific for identifying both planus and normal feet. FPI was most sensitive for identifying normal feet. The correlation between raw scores on the FPI and AI to CP were weak to moderate, -0.387 and -0.526, respectively (p<0.01). Conclusion: Surgeon observation is the only method that had a sensitivity over 0.50 for two different foot morphologies. FPI does not have the highest specificity for any particular foot type; however, a specificity of 0.844 and 0.971 for planus and cavus feet demonstrates that FPI is a suitable modality for evaluating pathologic morphology. Our specificity is close to a prior reported 0.932. These similarities in statistics reassure us that our methods are consistent with prior studies. Limitations of the study include small sample size and a single surgeon reviewing imaging. [Table: see text]
The purpose of this study was to investigate the relationship between tunnel position in ACL reconstruction (ACL-R) and postoperative meniscus tears.This was a single institution, case-control study of 170 patients status-post ACL-R (2010-2019) separated into two matched groups (sex, age, BMI, graft type). Group 1-symptomatic, operative meniscus tears (both de novo and recurrent) after ACL-R. Group 2-no postoperative meniscus tears. Femoral and tibial tunnel positions were measured by 2 authors via lateral knee radiographs that were used to measure two ratios (a/t and b/h). Ratio a/t was defined as distance from the tunnel center to dorsal most subchondral contour of the lateral femoral condyle (a) divided by total sagittal diameter of the lateral condyle along Blumensaat's line (t). The ratio b/h was defined as distance between the tunnel and Blumensaat's line (b) divided by maximum intercondylar notch height (h). Wilcoxon sign-ranks paired test was used to compare measurements between groups (alpha set at p < 0.05).Group 1 had average follow up of 45 months and Group 2 had average follow up of 22 months. There were no significant demographic differences between Groups 1 and 2. Group 1-a/t was 32.0% (± 10.2), which was significantly more anterior than group 2, 29.3% (± 7.3; p < 0.05). There was no difference in average femoral tunnel ratio b/h or tibial tunnel placement between groups.A relationship exists between more anterior/less anatomic femoral tunnel position and the presence of recurrent or de novo, operative meniscus tears after ACL-R. Surgeons performing ACL-R should strive for recreation of native anatomy via proper tunnel placement to maximize postoperative outcomes.Level III.
Category: Ankle, Hindfoot Introduction/Purpose: Restoration of bilateral symmetry is used clinically to evaluate surgical and conservative treatment outcomes. However, the degree of symmetry and differences between sexes in ankle kinematics in healthy individuals remain unknown. Because relative motion between the tibia, talus and calcaneus cannot be accurately measured using conventional skin- mounted motion capture systems, biplane radiography is emerging as the preferred technique to measure in vivo ankle kinematics during functional activities. Therefore, the aims of the present study were to use biplane radiography to determine the degree of bilateral symmetry in ankle kinematics in healthy individuals and to identify sex-dependent differences in kinematics during the support phase of gait. It was hypothesized that rotational ankle range of motion (ROM) during gait is not different between males and females. Methods: Twenty healthy individuals (10 male, 10 female, age 30.7 ± 6.3years) with no history of ankle injury provided consent to participate in this IRB-approved study. Each participant walked through a biplane radiography system 6 times at a self-selected pace (1.3±0.2 m/s). Synchronized radiographs of the ankle were collected at 100 images/second for 3 trials of each ankle (90 kV, 125 mA, 1 ms exposure/image). Motion of the tibia, talus and calcaneus was tracked using a validated model-based tracking process that matches 3D bone models to the radiographs. Anatomic coordinate systems were created and used to calculate ankle kinematics. All kinematics were converted to percent stance phase and averaged over all trials for each ankle. Bilateral symmetry was determined by calculating the average absolute difference between right and left ankle joint kinematics over the full support phase of gait. Differences between male and female rotational ROM were identified using unpaired t-tests. Results: The average absolute side-to-side difference in tibio-talar joint rotations was 3.3° or less, while the average absolute side-to-side difference in subtalar joint rotations was 3.0° or less (Table 1A). For males and females, at the tibio-talar joint, the largest ROM was plantar-dorsiflexion, followed by internal/external rotation and then inversion/eversion (Table 1B). At the subalar joint, the largest ROM was inversion/eversion, with similar amounts of dorsiflexion/plantarflexion and internal/external rotation, on the order of 2° to 3°. Males demonstrated significantly less ROM in subtalar dorsiflexion/plantarflexion and tibio-talar internal/external rotation (Table 1B). Conclusion: The average side-to-side differences in healthy ankle ROM during gait are small, suggesting that the contralateral ankle may serve as a reference standard to assess kinematic outcomes after conservative or surgical treatments. The difference between male and female subtalar ROM (0.6°) may be too small to be functionally significant, however, sex differences in tibio- talar ROM appear large enough to merit consideration when assessing functional outcomes and designing ankle joint replacements. The results are limited to over-ground gait performed by relatively young and healthy adults and may not be applicable to other activities or older adults.
