Christian Maiwald

Foot morphology of normal, underweight and overweight children

Objective:Due to the fact that there is a global increase in obesity, knowledge about the impact of obesity on the development of a childs foot is of great importance for orthopaedic and paediatric physicians with regard to prevention, clinical treatment and management. Therefore, the purpose of this study was to investigate the influence of body mass on the development of a childs foot based on a foot type classification.Methods:The feet of 1450 boys and 1437 girls aged 2–14 years were measured using a three-dimensional (3D) foot scanner (Pedus, Human Solutions Inc., Germany) in a bipedal upright position. Twelve relevant 3D foot measures were recorded, as well as the childrens age, gender, height and mass. Factor analysis of principal components was used to obtain a smaller number of independent and standardized variables. The variables were used for cluster analysis to classify the childrens feet.Results:Five foot types were identified: flat, robust, slender, short and long feet. There were significant differences among foot types with respect to the childrens body mass index. Normal weight children displayed an almost equal distribution of all foot types throughout childhood. Flat and robust feet were more common in overweight children, whereas underweight children showed more slender and long feet.Conclusion:The influence of excess, as well as deficient mass could be verified for the comprehensive foot morphology based on a foot type classification. Subsequently, foot discomfort as a result of various musculoskeletal disorders may develop. In turn, this might keep the children from being active and therefore reinforce the risk of developing obesity. However, there is still a lack of information regarding these relationships, which needs to be determined. This knowledge may help prevent orthopaedic foot problems and injuries.

Treatment of Chronic Achilles Tendinopathy and Ruptures with Flexor Hallucis Tendon Transfer: Clinical Outcome and MRI Findings:

Background: In patients with chronic Achilles tendinopathy, augmentation with flexor hallucis longus (FHL) tendon transfer can be performed to improve pain and functional limitations. There are no reports of postoperative imaging for evaluating tendon integration, inflammatory alterations or degeneration of the FHL muscle. The purpose of this study was to evaluate postoperative MR imaging based on clinical outcome and isokinetic strength. Materials and Methods: 13 patients with chronic Achilles tendinopathy (10 ruptures) underwent augmentation with FHL transfer. Clinical parameters, isokinetic strength and outcome measurements (AOFAS, SF-36) were evaluated at an average followup of 46.5 months. Qualitative and quantitative analyses of postoperative MRI were conducted using the non-operated side for comparison. Results: All patients had a significant reduction of pain. The operated side had a torque deficit of 35% for plantar flexion. Ten patients returned to their former level of activity. MRI showed a complete integration of the FHL tendon in six patients. Fatty atrophy in the triceps surae was found in ten patients. The FHL was free of degeneration in all patients. Hypertrophy of the FHL of more than 15% was observed in eight patients. Conclusion: Augmentation with FHL transfer is a valuable option in the treatment of chronic Achilles tendinopathy with and without rupture. Our results demonstrate high patient satisfaction without donor site morbidity. The FHL tendon is well integrated into the Achilles tendon. Hypertrophy of the FHL muscle suggests functional incorporation into plantar flexion. The primary benefit of the operation is pain relief and increased muscle strength.

Sex-related differences in foot shape

The purpose of the study was to investigate sex-related differences in foot morphology. In total, 847 subjects were scanned using a 3-D-footscanner. Three different analysis methods were used: (1) comparisons were made for absolute foot measures within 250–270 mm foot length (FL); (2) and for averaged measures (% FL) across all sizes; (3) the feet were then classified using a cluster analysis. Within 250–270 mm FL, male feet were wider and higher (mean differences (MD) 1.3–5.9 mm). No relevant sex-related differences could be found in the comparison of averaged measures (MD 0.3–0.6% FL). Foot types were categorised into voluminous, flat-pointed and slender. Shorter feet were more often voluminous, longer feet were more likely to be narrow and flat. However, the definition of ‘short’ and ‘long’ was sex-related; thus, allometry of foot measures was different. For shoe design, measures should be derived for each size and sex separately. Different foot types should be considered to account for the variety in foot shape. Improper footwear can cause foot pain and deformity. Therefore, knowledge of sex-related differences in foot measures is important to assist proper shoe fit in both men and women. The present study supplements the field of knowledge within this context with recommendations for the manufacturing of shoes.

Kinematic Analysis of Runners with Achilles Mid-Portion Tendinopathy

Background: Despite anecdotal evidence linking overpronation to the onset of Achilles tendinopathy (AT), there is little conclusive evidence of a particular movement pattern of the lower extremity associated with this injury. Therefore, the objective of the present study was to observe differences in the kinematic profiles of healthy runners (CON) and runners with mid-portion Achilles tendinopathy (ATG). Materials and Methods: In this cross-sectional analysis, 48 male height and weight matched subjects were invited to participate: 27 with mid-portion Achilles tendon pain and 21 asymptomatic controls. Subjects underwent lower extremity clinical examination, then ran barefoot for 10-trials at a self-selected pace. A 3D motion capture system analysed tri-plane kinematic data for the lower extremity. Results: The ATG displayed significantly greater sub-talar joint eversion displacement during mid-stance of the running gait (13 ± 3 degrees vs. 11 ± 3 degrees; p = 0.04). Trends were observed such that the ATG showed lower peak dorsiflexion velocity (300 ± 39 degrees/s vs. 330 ± 59 degrees/s; p = 0.08) and greater overall frontal plane ankle joint range of motion (45 degrees ± 7 vs. 41 degrees ± 7; p = 0.09). Conclusion: We found an increase in eversion displacement of the sub-talar joint in runners with Achilles mid-portion tendinopathy. Based on the findings from this study, there is evidence that devices used to control sub-talar eversion may be warranted in patients with Achilles mid-portion tendinopathy who demonstrate over-pronation during mid-stance of the running gait. Level of Evidence: III, Comparative Study

A new approach to children's footwear based on foot type classification

Current shoe designs do not allow for the comprehensive 3-D foot shape, which means they are unable to reproduce the wide variability in foot morphology. Therefore, the purpose of this study was to capture these variations of childrens feet by classifying them into groups (types) and thereby provide a basis for their implementation in the design of childrens shoes. The feet of 2867 German children were measured using a 3-D foot scanner. Cluster analysis was then applied to classify the feet into three different foot types. The characteristics of these foot types differ regarding their volume and forefoot shape both within and between shoe sizes. This new approach is in clear contrast to previous systems, since it captures the variability of foot morphology in a more comprehensive way by using a foot typing system and therefore paves the way for the unimpaired development of childrens feet. Previous shoe systems do not allow for the wide variations in foot morphology. A new approach was developed regarding different morphological foot types based on 3-D measurements relevant in shoe construction. This can be directly applied to create specific designs for childrens shoes.

What are causes and treatment strategies for patellar-tendinopathy in female runners?

Patellar-tendinopathy (PT) is a common overuse injury in long distance runners, especially in women. Until today, no definite combinations of clinical, biomechanical, or training variables, or causative factors in the development of PT have been found. This study focused on assessing the differences in biomechanical characteristics between healthy runners (CO) and runners with PT only. We examined a total of 42 women. 21 CO and 21 PT. 3D kinematics of barefoot running was used in the biomechanical setup. Both groups were matched with respect to height and weight. After determining dropouts due to forefoot running, poor quality of data and lack of matching subjects in CO in terms of body height and weight, the final population comprised 24 subjects (CO=12, PT=12). Biomechanical evaluations indicate eccentric overloading of the quadriceps muscle group (knee extensors), increased pronation velocity as well as a lack of joint coordination as major etiological factors in the development of PT. We assume that eccentric strengthening of the knee extensors, as well as reduction of pronation velocity through orthotics, proper running shoes, and balance training will help treat and possibly prevent PT.

Kinematic classification of iliotibial band syndrome in runners

Several inconsistent causative biomechanical factors are considered to be crucial in the occurrence of iliotibial band syndrome (ITBS). The focus of this study was on assessing differences in the kinematic characteristics between healthy runners [control group (CO)] and runners with ITBS in order to recommend treatment strategies to deal with this injury. Three‐dimensional kinematics of barefoot running was used in the biomechanical setup. Both groups were matched with respect to gender, height and weight. After determining drop outs, the final population comprised 36 subjects (26 male and 10 female): 18 CO and 18 ITBS (13 male and five female, each). Kinematic evaluations indicate less hip adduction and frontal range of motion at the hip joint in runners with ITBS. Furthermore, maximum hip flexion velocity and maximum knee flexion velocity were lower in runners with ITBS. Lack of joint coordination, expressed as earlier hip flexion and a tendency toward earlier knee flexion, was found to be another discriminating variable in subjects with ITBS compared with CO subjects. We assume that an increase in range of motion at the hip joint, stretching of the hip abductors, as well as stretching the hamstrings, calf muscles and hip flexors will help treat ITBS.

Using the variability of continuous relative phase as a measure to discriminate between healthy and injured runners

Several studies have used variability of continuous relative phase (CRP) to investigate overuse injuries, since low variability is thought to be related to running injuries. This study investigates whether the analysis of CRP variability leads to additional information about possible differences or similarities between healthy and injured runners. Further, a decision about future applications of CRP variability should be based on the ability to implement and interpret data. 18 healthy female runners (CO) and 18 female runners who suffered from iliotibial band syndrome (ITBS) were evaluated by calculating CRP variability for 4 coupling pairs. Besides analyzing continuous variability of CRP, we also averaged it for the whole stance phase and for four predefined stance phase intervals. Confidence intervals were displayed and independent t-tests for comparing the two groups were conducted. During initial and terminal stance phase as well as after heel-off an increase in CRP variability was detected for both groups of runners. In contrast, the foot flat period was characterized by stable joint coordination and a decrease in variability. This paper presents possible interpretations of CRP variability but no statistically significant differences in CRP variability were found between the two groups of runners. Despite the missing statistical significance, a relationship between high CRP variability and injury seems to be conceivable, since the injured runners demonstrated an increased variability for all couplings in the first half of the stance phase. Further application of CRP variability in biomechanical research is essential to determine whether a relationship exists between injury and coordination variability.

Detecting foot-to-ground contact from kinematic data in running

Determining foot touchdown and foot takeoff is an essential part of gait analysis protocols and is usually accomplished using force plate data and thresholds for the vertical component of the ground reaction force (GRF). It has been proposed that gait events can also be estimated from kinematic data, and several algorithms have already been published. However, many of these algorithms were designed and specified for application in walking gait only. Hence, the purpose of this paper is to present our newly developed foot contact algorithm (FCA) and compare its estimation accuracy for touchdown and takeoff to a selection of existing algorithms. Forty one subjects were analyzed in a laboratory setup recording ground reaction forces and 3D-kinematic data of the lower limbs during running in three different running shoes. Prediction error of touchdown and takeoff was quantified in relation to gold standard events determined from force-plate data. Out of the evaluated algorithms, only FCA was able to estimate touch down and take off with similar precision, and is recommended when analyzing running gait. Furthermore, we found no evidence that different running shoes influenced the prediction error for any of the used algorithms.

The influence of matching populations on kinematic and kinetic variables in runners with iliotibial band syndrome.

The purpose of this study was to assess how participant matching influences biomechanical variables when comparing healthy runners and runners with iliotibial band syndrome (ITBS). We examined 52 healthy runners (CO) and 18 with ITBS, using three-dimensional kinematics and pressure distribution. The study population was matched in three ways and compared with the biomechanical findings: ITBS versus CO I (unmatched), ITBS versus CO II (matched to gender) and ITBS versus CO III (matched to gender, height, and weight). The final number of participants in each group was n = 18. The kinematic variables showed a dependency on the matching process. The largest statistically significant differences (after Bonferroni adjustment) in the frontal and transverse planes were between ITBS and CO III (p = .008). Pressure measurements were also dependent on the matching process, with decreasing and nonsignificant differences (p = .006) between ITBS and CO after refining the process (ITBS vs. CO III). The results of this study and the necessity of matching seem to be plausible (lever arms, different running styles). Data matching is important for understanding overuse injuries in running.