Frank E. DiLiberto

Alterations in Plantar Pressure with Different Walking Boot Designs

Background: Specialized walking devices, such as total contact casts and removable walking boots, have been shown to be effective noninvasive treatment options for plantar ulcers. Attempts at improving patient compliance frequently lead to new boot designs; however, the effect of the design modifications on plantar pressures or on the contralateral limb often is unknown. The purpose of this study was to determine the effect of different walking-boot calf heights and rocker sole designs on regional plantar pressures, as well as, on contralateral limb loading during walking. Methods: Twenty-six subjects, 20 to 54 years of age, without foot pathology were tested using four different configurations: high calf, rocker sole (HCR); low calf, rocker sole (LCR); low calf, modified rocker sole (LCMR), and shoe. Peak pressures, pressure-time integrals, and contact areas were measured using the Novel Pedar-X insole pressure measurement system. Average peak force was calculated for the contralateral limb. Results: Greatest forefoot peak pressure reduction was found in the HCR group (37.3% reduction compared to shoe condition), followed by 31.6% and 19.8% in the LCR and LCMR groups, respectively (p < 0.0001). Forefoot pressure-time integrals were reduced for HCR and LCR (22.1% and 21.5%, respectively) compared to the LCMR (13.0%) (p < 0.0001). Conclusions: Isolated modifications in walking boot designs resulted in plantar pressure modifications. LCR and LCMR designs favorably altered plantar pressures, but of a lesser magnitude than the HCR design. If lower calf, lower sole walking boot designs are recommended because of anticipated improvement in patient compliance, healing times may be prolonged.

Ankle Power and Endurance Outcomes Following Isolated Gastrocnemius Recession for Achilles Tendinopathy

Background: Studies have demonstrated improved ankle dorsiflexion and pain reduction following a gastrocnemius recession (GR) procedure. However, changes in muscle performance during functional activities are not known. The purpose of this study was to determine the effect of an isolated GR on ankle power and endurance in patients with Achilles tendinopathy. Methods: Fourteen patients with chronic unilateral Achilles tendinopathy and 10 healthy controls participated in this study. Patient group data were collected 18 months following GR. Pain was compared to preoperative values using a 10-cm visual analog scale (VAS). Patient-reported outcomes for activities of daily living (ADL) and sports were assessed using the Foot and Ankle Ability Measure (FAAM). Kinematic and kinetic data were collected during gait, stair ascent (standard and high step), and repetitive single-limb heel raises. Between-group and side-to-side differences in ankle plantarflexor muscle power and endurance were evaluated with appropriate t tests. Results: Compared with preoperative data, VAS pain scores were reduced (pre 6.8, post 1.6, P < .05). Significant differences were observed between GR and Control groups for FAAM scores for both ADL (GR 90.0, Control 98.3, P = .01) and Sports subscales (GR 70.6, Control 94.6, P = .01). When compared to controls, ankle power was reduced in the involved limb of the GR group for all activities (all P < .05). Between-group and side-to-side deficits (GR group only) were also found for ankle endurance. Conclusion: The gastrocnemius recession procedure provided significant pain reduction that was maintained at the 18-month follow-up for patients with chronic Achilles tendinopathy who failed nonoperative interventions. There were good patient-reported outcomes for activities of daily living. However, compared to controls, ankle plantarflexion power and endurance deficits in the GR group were noted. The functional implications of the muscle performance deficits are unclear, but may be reflective of patients’ self-reported difficulty during more challenging activities. Level of Evidence: Level III, comparative study.

The prevention of diabetic foot ulceration: how biomechanical research informs clinical practice

ABSTRACT Background Implementation of interprofessional clinical guidelines for the prevention of neuropathic diabetic foot ulceration has demonstrated positive effects regarding ulceration and amputation rates. Current foot care recommendations are primarily based on research regarding the prevention of ulcer recurrence and focused on reducing the magnitude of plantar stress (pressure overload). Yet, foot ulceration remains to be a prevalent and debilitating consequence of Diabetes Mellitus. There is limited evidence targeting the prevention of first-time ulceration, and there is a need to consider additional factors of plantar stress to supplement current guidelines. Objectives The first purpose of this article is to discuss the biomechanical theory underpinning diabetic foot ulcerations and illustrate how plantar tissue underloading may precede overloading and breakdown. The second purpose of this commentary is to discuss how advances in biomechanical foot modeling can inform clinical practice in the prevention of first-time ulceration. Discussion Research demonstrates that progressive weight-bearing activity programs to address the frequency of plantar stress and avoid underloading do not increase ulceration risk. Multi-segment foot modeling studies indicate that dynamic foot function of the midfoot and forefoot is compromised in people with diabetes. Emerging research demonstrates that implementation of foot-specific exercises may positively influence dynamic foot function and improve plantar stress in people with diabetes. Conclusion Continued work is needed to determine how to best design and integrate activity recommendations and foot-specific exercise programs into the current interprofessional paradigm for the prevention of first-time ulceration in people with Diabetes Mellitus.

Multi-joint foot kinetics during walking in people with Diabetes Mellitus and peripheral neuropathy

Neuropathic tissue changes can alter muscle function and are a primary reason for foot pathologies in people with Diabetes Mellitus and peripheral neuropathy (DMPN). Understanding of foot kinetics in people with DMPN is derived from single-segment foot modeling approaches. This approach, however, does not provide insight into midfoot power and work. Gaining an understanding of midfoot kinetics in people with DMPN prior to deformity or ulceration may help link foot biomechanics to anticipated pathologies in the midfoot and forefoot. The purpose of this study was to evaluate midfoot (MF) and rearfoot (RF) power and work in people with DMPN and a healthy matched control group. Thirty people participated (15 DMPN and 15 Controls). An electro-magnetic tracking system and force plate were used to record multi-segment foot kinematics and ground reaction forces during walking. MF and RF power, work, and negative work ratios were calculated and compared between groups. Findings demonstrated that the DMPN group had greater negative peak power and reduced positive peak power at the MF and RF (all p≤0.05). DMPN group negative work ratios were also greater at the MF and RF [Mean difference MF: 9.9%; p=0.24 and RF: 18.8%; p<0.01]. In people with DMPN, the greater proportion of negative work may negatively affect foot structures during forward propulsion, when positive work and foot stability should predominate. Further study is recommended to determine how both MF and RF kinetics influence the development of deformity and ulceration in people with DMPN.

Individual metatarsal and forefoot kinematics during walking in people with diabetes mellitus and peripheral neuropathy

The purpose of this study was to compare in-vivo kinematic angular excursions of individual metatarsal segments and a unified forefoot segment in people with Diabetes Mellitus and peripheral neuropathy (DMPN) without deformity or ulceration to a healthy matched control group. Thirty subjects were recruited. A five- segment foot model (1st, 3rd, and 5th metatarsals, calcaneus, tibia) was used to examine relative 3D angular excursions during the terminal stance phase of walking. Student t-tests were used to assess group differences in kinematics. Pearson correlations and cross-correlations were used to assess relationships between the motion of the individual metatarsals and the unified forefoot. Significant reductions of DMPN group sagittal plane angular excursions were detected in all individual metatarsals and the unified forefoot (p < 0.01). Frontal plane 3rd metatarsal excursion was reduced (p = 0.04) in the DMPN group. The 3rd and 5th metatarsal and the unified forefoot excursions were reduced (p ≤ 0.02) in the DMPN group in the transverse plane. In both groups, coupling of individual metatarsal and unified forefoot motion was strongest in the sagittal plane. This study illustrates that multiple individual metatarsals have reduced motion in people with DMPN. Differences in the magnitude and coupling between individual metatarsal motion and unified forefoot motion supports the use of a two segment forefoot modeling approach in future kinematic analyses. Further study is recommended to determine if the observed kinematic profile is related to the development and location of deformity and tissue breakdown in people with DMPN.

Ankle and Midfoot Power During Walking and Stair Ascent in Healthy Adults

Ankle power dominates forward propulsion of gait, but midfoot power generation is also important for successful push-off. However, it is unclear if midfoot power generation increases or stays the same in response to propulsive activities that induce larger external loads and require greater ankle power. The purpose of this study was to examine ankle and midfoot power in healthy adults during progressively more demanding functional tasks. Multisegment foot motion (tibia, calcaneus, and forefoot) and ground reaction forces were recorded as participants (N = 12) walked, ascended a standard step, and ascended a high step. Ankle and midfoot positive peak power and positive total power, and the proportion of midfoot to ankle positive total power were calculated. One-way repeated-measures analyses of variance were conducted to evaluate differences across tasks. Main effects were found for ankle and midfoot peak and total powers (all Ps < .01), but not for the proportion of midfoot-to-ankle total power (P = .33). Ankle and midfoot power significantly increased across each task. Midfoot power increased in proportion to ankle power and in congruence to the external load of a task. Study findings may serve to inform multisegment foot modeling applications and internal mechanistic theories of normal and pathological foot function.

Does Ankle Muscle Performance Mirror Improved Pain Following Total Ankle Arthroplasty

Category: Ankle Arthritis Introduction/Purpose: Total ankle arthroplasty (TAA) outcomes include pain reduction and improved gait speed. Ankle push off power, which requires gastroc-soleus muscle strength, is a critical aspect of healthy gait and increases as gait speed increases. It appears that improvements in pain translate to improved ankle muscle performance. However, ankle power after TAA is surprisingly low. It is possible years of arthritis and latent muscle memory result in reduced gastroc-soleus muscle strength and a gait pattern reliant on proximal joints for power. Evaluating these hypotheses will drive postoperative care. The purpose of this ongoing prospective study is to be the first to evaluate the interplay of pain, gait speed, and ankle muscle performance (strength and power) in people following TAA for end-stage ankle arthritis. Methods: Twelve people [Mean (SD): Age 61 (14.3) years; BMI 30.0 (5.4) Kg/m2; 83% male] with end-stage ankle arthritis who were candidates for TAA participated (12 preoperative and 9 six-month postoperative visits). Performance of adjunct soft tissue procedures and postoperative care were patient specific. A twenty point numeric pain rating scale was used to measure worst pain in the past week. Three dimensional multi-segment foot motion analysis was performed while participants walked barefoot on level ground over a force plate. Ankle peak push-off power (joint torque x segmental velocity) was calculated. Ankle peak isokinetic plantarflexion strength (torque at 60 degrees / second) and ankle sagittal plane passive range of motion were measured with a dynamometer. Participants also completed the six minute walk test. Wilcoxon Signed Rank tests were used to evaluate preoperative to postoperative changes and between limb differences postoperatively. Results: Pain decreased (postoperative mean = 2.8; p = 0.01) and gait speed increased following TAA (p = 0.02). Ankle plantarflexion strength and ankle power during walking were preserved following TAA (both p > 0.8) (Figure 1). Postoperative group mean dorsiflexion was 25.1 degrees and plantarflexion was 18.9 degrees, suggesting sufficient ankle motion was present for plantarflexor muscle performance. However, between limb differences were significant for both strength and power (both p < 0.05) postoperatively. The involved ankle produced 36% less strength and generated 45% less power during walking in comparison to the uninvolved limb. This asymmetry demonstrates that involved limb ankle muscle performance was not normalized at six-month follow up, despite improvements in pain. Conclusion: Study findings provide preliminary evidence that improved pain and gait speed are disconnected from ankle muscle performance following TAA. Postoperative improvements in gait speed were likely driven by more proximal joints (i.e. hip). Without additional targeted postoperative plantarflexion strengthening and gait training to improve ankle muscle involvement, gains in ankle power, a symmetrical gait pattern, and patient tolerance to higher level activity (i.e. stairs) are unlikely to occur long-term. The underpinning mechanisms limiting the necessary strength to drive power generation (i.e. length-tension relationship, atrophy), and the possible cumulative effect of how abnormal gait may influence implant survivorship deserve further attention.

Prospective Analysis of Isolated Gastrocnemius Recession for Achilles Tendinopathy; Intermediate Follow-up

Category: Ankle Introduction/Purpose: Gastrocnemius recession (GR) has emerged as a potential alternative to traditional surgical treatments in patients with recalcitrant Achilles tendinopathy (AT). Recent retrospective studies have shown positive results. However, there is limited long-term prospective data regarding the results of this surgery. We are reporting two-year results of a prospective analysis of isolated GR for Achilles tendinopathy on pain, self reported function, and satisfaction. Methods: 8 patients (mean age 52± 10.2 years) with chronic unilateral AT (> 6 months duration) and an isolated gastrocnemius contracture participated. All subjects received a GR (Strayer) procedure. Data were collected pre- and post-operatively at 6 months and 2 years. Pain and function were assessed using the Visual Analog Scale(VAS) and the Foot and Ankle Ability Measure(FAAM). Clinical measure of calf endurance was assessed by single limb heel raises and compared to the uninvolved limb. Calf circumference was evaluated and patients were queried regarding satisfaction with the GR procedure and need for further treatment. Descriptive analysis was used to assess changes across the repeated timelines. Results: All subjects returned at 6 month follow-up and 7/8 patients participated in the final follow-up (mean 23 +/- 5.5 months). Pain was reduced by 50% at 6 months and 90% at 2 years; with 6 of 7 subjects reporting no pain. Pre-op FAAM ADL subscale was 75%, improving to 90% and 97% at 6 months and 2 years, respectively. Pre-op FAAM Sports subscale was 40%, improving to 69% and 87% at 6 months and 2 years, respectively. There were no side-to-side differences in the number of heel raises performed across time frames; involved mean 26 +/- 7, uninvolved 28 +/-6. Five (of seven) subjects reported complete satisfaction with the procedure and two were satisfied with minor reservations. Conclusion: To our knowledge, this is the first study to prospectively evaluate an isolated GR for Achilles tendinopathy and present 6 month and 2-year follow-up data. Pain relief was markedly decreased and maintained at 2 years. FAAM ADL activities were restored to normative values. However, scores for the FAAM sports subscale remained slightly below normative values and may reflect patient reported difficulties with higher-level activities such as jumping and lateral movements. High satisfaction can be expected for the majority of patients, however patients engaged in higher demand activities may have a prolonged recovery period and persistent limitations.