A toe-inspired rigid-flexible coupling wheel design method for improving the terrain adaptability of a sewer robot.

The human toe, characterized by its rigid-flexible structure comprising hard bones and flexible joints, facilitates adaptive and stable movement across varied terrains. In this paper, we utilized a motion capture system to study the adaptive adjustments of toe joints when encountering obstacles. Inspired by the mechanics of toe joints, we proposed a novel design method for a rigid-flexible coupled wheel. The wheel comprises multiple elements: a rigid skeleton, supporting toes, connecting shafts, torsion springs, soft tendons, and damping pads. The torsion springs connect the rigid frame to the supporting toes, enabling them to adapt to uneven terrains and pipes with different diameters. The design was validated through kinematic and dynamic modeling, rigid-flexible coupled dynamics simulation, and stress analysis. Different stiffness coefficients of torsion springs were compared for optimal wheel design. Then, the wheel was applied to a sewer robot, and its performance was evaluated and compared with a pneumatic rubber tire in various experiments, including movement on flat surfaces, overcoming small obstacles, adaptability tests in different terrains, and active driving force tests in dry and wet pipelines. The results prove that the designed wheel showed better stability and anti-slip properties than conventional tires, making it suitable for diverse applications such as pipeline robots, desert vehicles, and lunar rovers.

Effect of the upward curvature of toe springs on walking biomechanics in humans.

Although most features of modern footwear have been intensively studied, there has been almost no research on the effects of toe springs. This nearly ubiquitous upward curvature of the sole at the front of the shoe elevates the toe box dorsally above the ground and thereby holds the toes in a constantly dorsiflexed position. While it is generally recognized that toe springs facilitate the forefoot's ability to roll forward at the end of stance, toe springs may also have some effect on natural foot function. This study investigated the effects of toe springs on foot biomechanics in a controlled experiment in which participants walked in specially-designed sandals with varying curvature in the toe region to simulate toe springs ranging from 10 to 40 degrees of curvature. Using inverse dynamics techniques, we found that toe springs alter the joint moments and work at the toes such that greater degrees of toe spring curvature resulted in lower work requirements during walking. Our results help explain why toe springs have been a pervasive feature in shoes for centuries but also suggest that toe springs may contribute to weakening of the foot muscles and possibly to increased susceptibility to common pathological conditions such as plantar fasciitis.

Effects of toe length, foot arch length and toe joint axis on walking biomechanics.

Toe joint articulation has been shown to affect gait mechanics, as evidenced by walking simulations, biped robots, and foot prostheses. However, it is not known how parameters such as toe length, foot arch length (i.e., heel-to-toe-joint length) or toe joint axis angle affect human walking. We utilized a previously developed adjustable ankle-toe prosthesis to systematically examine these three foot parameters. We tested ten able-bodied persons walking on a force instrumented-treadmill while wearing a pair of adjustable prostheses attached bilaterally below simulator boots (which fixated their biological ankles). We collected motion and ground reaction force data to compute lower-limb kinematics and kinetics as well as COM power and work. We observed that increasing the foot arch length by 60 mm (35%) increased COM Push-off work by ~5 J, due to increased energy storage and return by the ankle spring. Increasing the toe length by 40 mm (80%) and changing the toe joint axis by ±9° from a neutral angle resulted in negligible effects on COM mechanics and lower limb kinetics. This study provides further insights regarding toe joint function; knowledge which may benefit the design/integration of toe joints into prostheses, exoskeletons and legged robots.

The Impact of a Foot-Toe Orthosis on Dynamic Balance: An Exploratory Randomized Control Trial.

CONTEXT: The influence of custom and over-the-counter foot orthoses on dynamic balance has been investigated in the past. However, there has not been an exploration of the use of a foot-toe orthosis for improving balance. The ability of clinicians to influence balance could have important implications for injury prevention and rehabilitation. OBJECTIVE: To determine the impact of a foot-toe orthosis on dynamic balance in healthy, young adults. DESIGN: Randomized control trial. SETTING: Athletic training laboratory. PARTICIPANTS: In total, 64 healthy, recreationally active participants aged 18-29 years were randomly allocated to one of the following groups: the foot-toe orthosis and laboratory-issued shoe group, the laboratory-issued shoe only (SO) group, or the control group. INTERVENTIONS: Subjects in the intervention group wore the foot-toe orthosis and laboratory-issued shoe with activities of daily living for 4 weeks. Subjects in the SO intervention group wore the laboratory-issued shoe with activities of daily living for 4 weeks. Participants in the control group did not receive any intervention. MAIN OUTCOME MEASURES: The instrumented version of the Star Excursion Balance Test, known as the Lower Quarter Y-Balance Test, was used to quantify the dynamic balance at baseline and follow-up. Reaches were normalized for leg length. RESULTS: There were statistically significant differences in postintervention scores on the Lower Quarter Y-Balance Test for both the dominant (P = .03, effect size = 0.84; 95% confidence interval, 0.25 to 1.43) and nondominant (P = .002, effect size = 0.74; 95% confidence interval, 0.15 to 1.32) legs when comparing dynamic balance scores of the foot-toe orthosis and laboratory-issued shoe group with the SO and control groups. No significant differences were observed when comparing dynamic balance between the SO and control groups. CONCLUSIONS: A 4-week intervention with a foot-toe orthosis and laboratory-issued shoe resulted in improved dynamic balance in a healthy young adult population. These findings suggest a novel intervention for increasing balance.

Functional assessments of foot strength: a comparative and repeatability study.

BACKGROUND: Evaluating the strength of the small muscles of the foot may be useful in a variety of clinical applications but is challenging from a methodology standpoint. Previous efforts have focused primarily on the functional movement of toe flexion, but clear methodology guidelines are lacking. A novel foot doming test has also been proposed, but not fully evaluated. The purposes of the present study were to assess the repeatability and comparability of several functional foot strength assessment techniques. METHODS: Forty healthy volunteers were evaluated across two testing days, with a two-week doming motion practice period between them. Seven different measurements were taken using a custom toe flexion dynamometer (seated), custom doming dynamometer (standing), and a pressure mat (standing). Measurements from the doming dynamometer were evaluated for reliability (ICCs) and a learning effect (paired t-tests), while measurements from the toe flexion dynamometer and pressure mat were evaluated for reliability and comparability (correlations). Electromyography was also used to descriptively assess the extent of muscle isolation in all measurements. RESULTS: Doming showed excellent within-session reliability (ICCs > 0.944), but a clear learning effect was present, with strength (p < 0.001) and muscle activity increasing between sessions. Both intrinsic and extrinsic muscles were engaged during this test. All toe flexion tests also showed excellent reliability (ICCs > 0.945). Seated toe flexion tests using the dynamometer were moderately correlated to standing toe flexion tests on a pressure mat (r > 0.54); however, there were some differences in muscle activity. The former may better isolate the toe flexors, while the latter appeared to be more functional for many pathologies. On the pressure mat, reciprocal motion appeared to display slightly greater forces and reliability than isolated toe flexion. CONCLUSIONS: This study further refines potential methodology for foot strength testing. These devices and protocols can be duplicated in the clinic to evaluate and monitor rehabilitation progress in clinical populations associated with foot muscle weakness.

Combined effects of knee brace, laterally wedged insoles, and toe-out gait on knee adduction moment and fall risk in moderate medial knee osteoarthritis patients.

BACKGROUND:: Knee osteoarthritis is a major contributor to the global burden of disease. There is a need of reducing knee joint load and to improve balance and physical function among knee osteoarthritis patients. OBJECTIVES:: To test the hypothesis that toe-out gait will reduce second peak knee adduction moment further and increase fall risk when combined with knee brace and laterally wedged insole in knee osteoarthritis patients. STUDY DESIGN:: Single visit study with repeated measures. METHODS:: First and second peak knee adduction moments, fall risk and comfort level. First and second peak knee adduction moments were determined from three-dimensional gait analysis, completed under six randomized conditions: (1) natural, (2) knee brace, (3) knee brace + toe-out gait, (4) laterally wedged insole, (5) laterally wedged insole + toe-out gait, and (6) knee brace + laterally wedged insole + toe-out gait. Fall risk was assessed by Biodex Balance System using three randomized stability settings: (1) static, (2) moderate dynamic setting (FR12), and (3) high dynamic setting (FR8). RESULTS:: The reduction in first peak knee adduction moment and second peak knee adduction moment was greatest (7.16% and 25.55%, respectively) when toe-out gait combine with knee brace and laterally wedged insole. Significant increase in fall risk was observed with knee brace + laterally wedged insole + toe-out gait (42.85%) at FR12. Similar significant balance reductions were found at FR8 condition for knee brace + toe-out gait (35.71%), laterally wedged insole + toe-out gait (28.57%), and knee brace + laterally wedged insole + toe-out gait (50%) as compared to natural. However, knee brace decreased fall risk at FR12 by 28.57%. CONCLUSION:: There is a synergistic effect of toe-out when combined with knee brace and laterally wedged insole concurrently in second peak knee adduction moment reduction but with a greater degree of fall risk. Simultaneous use of conservative treatments also decreases comfort level. CLINICAL RELEVANCE: Patients with mild and moderate knee osteoarthritis are usually prescribed conservative treatment techniques. This study will provide an insight whether or not a combination of these techniques have a synergistic effect in reducing knee joint load.

Effect of toe joint stiffness and toe shape on walking biomechanics.

During typical human walking, the metatarsophalangeal joints undergo extension/flexion, which we term toe joint articulation. This toe joint articulation impacts locomotor performance, as evidenced by prior studies on prostheses, footwear, sports and humanoid robots. However, a knowledge gap exists in our understanding of how individual toe properties (e.g. shape, joint stiffness) affect bipedal locomotion. To address this gap, we designed and built a pair of adjustable foot prostheses that enabled us to independently vary different toe properties, across a broad range of physiological and non-physiological values. We then characterized the effects of varying toe joint stiffness across a range of different ankle joint stiffness conditions, and the effects of varying toe shape on walking biomechanics. Ten able-bodied individuals walked on a treadmill with prostheses mounted bilaterally underneath simulator boots (which immobilized their biological ankles). We collected motion capture and ground reaction force data, then computed joint kinematics and kinetics, and center-of-mass (COM) power and work. To our surprise, we found that varying toe joint stiffness affected COM Push-off dynamics during walking as much as, or in some cases even more than, varying ankle joint stiffness. Increasing toe joint stiffness increased COM Push-off work by up to 48% (6 J), and prosthetic anklefoot Push-off work by up to 181% (12 J). In contrast, large changes in toe shape had little effect on gait. This study brings attention to the toes, an aspect of prosthetic and robotic foot design that is often overlooked or overshadowed by design of the ankle. Optimizing toe joint stiffness in assistive and robotic devices (e.g. prostheses, exoskeletons, robot feet) may provide a complementary means of enhancing Push-off or other aspects of locomotor performance, in conjunction with the more conventional approach of augmenting ankle dynamics. Future studies are needed to isolate the effects of additional toe properties (e.g. toe length).

Reliability of doming and toe flexion testing to quantify foot muscle strength.

BACKGROUND: Quantifying the strength of the intrinsic foot muscles has been a challenge for clinicians and researchers. The reliable measurement of this strength is important in order to assess weakness, which may contribute to a variety of functional issues in the foot and lower leg, including plantar fasciitis and hallux valgus. This study reports 3 novel methods for measuring foot strength - doming (previously unmeasured), hallux flexion, and flexion of the lesser toes. METHODS: Twenty-one healthy volunteers performed the strength tests during two testing sessions which occurred one to five days apart. Each participant performed each series of strength tests (doming, hallux flexion, and lesser toe flexion) four times during the first testing session (twice with each of two raters) and two times during the second testing session (once with each rater). Intra-class correlation coefficients were calculated to test for reliability for the following comparisons: between raters during the same testing session on the same day (inter-rater, intra-day, intra-session), between raters on different days (inter-rater, inter-day, inter-session), between days for the same rater (intra-rater, inter-day, inter-session), and between sessions on the same day by the same rater (intra-rater, intra-day, inter-session). RESULTS: ICCs showed good to excellent reliability for all tests between days, raters, and sessions. Average doming strength was 99.96 ± 47.04 N. Average hallux flexion strength was 65.66 ± 24.5 N. Average lateral toe flexion was 50.96 ± 22.54 N. CONCLUSIONS: These simple tests using relatively low cost equipment can be used for research or clinical purposes. If repeated testing will be conducted on the same participant, it is suggested that the same researcher or clinician perform the testing each time for optimal reliability.

Effects of a leaf spring structured midsole on joint mechanics and lower limb muscle forces in running.

To enhance running performance in heel-toe running, a leaf spring structured midsole shoe (LEAF) has recently been introduced. The purpose of this study was to investigate the effect of a LEAF compared to a standard foam midsole shoe (FOAM) on joint mechanics and lower limb muscle forces in overground running. Nine male long-distance heel strike runners ran on an indoor track at 3.0 ± 0.2 m/s with LEAF and FOAM shoes. Running kinematics and kinetics were recorded during the stance phase. Absorbed and generated energy (negative and positive work) of the hip, knee and ankle joint as well as muscle forces of selected lower limb muscles were determined using a musculoskeletal model. A significant reduction in energy absorption at the hip joint as well as energy generation at the ankle joint was found for LEAF compared to FOAM. The mean lower limb muscle forces of the m. soleus, m. gastrocnemius lateralis and m. gastrocnemius medialis were significantly reduced for LEAF compared to FOAM. Furthermore, m. biceps femoris showed a trend of reduction in running with LEAF. The remaining lower limb muscles analyzed (m. gluteus maximus, m. rectus femoris, m. vastus medialis, m. vastus lateralis, m. tibialis anterior) did not reveal significant differences between the shoe conditions. The findings of this study indicate that LEAF positively influenced the energy balance in running by reducing lower limb muscle forces compared to FOAM. In this way, LEAF could contribute to an overall increased running performance in heel-toe running.

Effects of Age on Strength and Morphology of Toe Flexor Muscles.

Study Design Descriptive, cross-sectional. Background Age-related muscle atrophy is common in lower-limb muscles. We therefore speculated that foot muscles may also diminish with age. However, there is a paucity of literature characterizing foot muscle strength and morphology, and any relationship between these 2, in older people. Objective To compare the strength and size of the toe flexor muscles of older adults relative to their younger counterparts. Methods Seventeen young adults with a normal foot type were matched by sex and body mass index to 17 older adults with a normal foot type, from an available sample of 41 younger (18 to 50 years of age) and 44 older (60 or more years of age) adults. Among the matched groups (n = 34), muscle thickness and cross-sectional area for 5 intrinsic and 2 extrinsic toe flexor muscles were obtained using ultrasound. Toe strength was assessed using a pressure platform. Differences in toe flexor strength and muscle size between the young and older matched groups were determined using analysis of covariance (controlling for height). Correlations between strength and size of the toe flexor muscles of the pooled group (n = 34) were also calculated. Results Toe strength and the thickness and cross-sectional area of most foot muscles were significantly reduced in the older adults (P<.05). Hallux and toe flexor strength values were strongly correlated with the size of the intrinsic toe flexor muscles. Conclusion The smaller foot muscles appear to be affected by sarcopenia in older adults. This could contribute to reduced toe flexion force production and may affect the ability of older people to walk safely. Interventions aimed at reversing foot muscle atrophy in older people require further investigation. J Orthop Sports Phys Ther 2016;46(12):1065-1070. Epub 29 Oct 2016. doi:10.2519/jospt.2016.6597.

The Applicability of Plantar Padding in Reducing Peak Plantar Pressure in the Forefeet of Healthy AdultsImplications for the Foot at Risk.

BACKGROUND: We investigated the effectiveness and durability of two types of plantar padding, the plantar metatarsal pad and the single wing plantar cover, which are commonly used for reducing forefoot plantar pressures. METHODS: Mean peak plantar pressure and impulse at the hallux and at the first, second, third, and fourth metatarsophalangeal joints across both feet were recorded using the two-step method in 18 individuals with normal asymptomatic feet. Plantar paddings were retained for 5 days, and their durability and effectiveness were assessed by repeating the foot plantar measurement at baseline and after 3 and 5 days. RESULTS: The single wing plantar cover devised from 5-mm felt adhesive padding was effective and durable in reducing peak plantar pressure and impulse at the first metatarsophalangeal joint (P = .001 and P = .015, respectively); however, it was not found to be effective in reducing peak plantar pressure and impulse at the hallux (P = .782 and P = .845, respectively). The plantar metatarsal pad was not effective in reducing plantar forefoot pressure and impulse at the second, third, and fourth metatarsophalangeal joints (P = .310 and P = .174, respectively). CONCLUSIONS: These results imply limited applicability of the single wing plantar cover and the plantar metatarsal pad in reducing hallux pressure and second through fourth metatarsophalangeal joint pressure, respectively. However, the single wing plantar cover remained durable for the 5 days of the trial and was effective in reducing the peak plantar pressure and impulse underneath the first metatarsophalangeal joint.

Effect of Regional Intravenous Limb Perfusate Volume on Synovial Fluid Concentration of Amikacin and Local Venous Blood Pressure in the Horse.

OBJECTIVE: To determine the effect of volume of amikacin perfusate for intravenous regional limb perfusion (IVRLP) via the cephalic vein in standing, sedated horses on (1) amikacin concentrations in the synovial fluid of the radiocarpal joint (RCJ) and distal interphalangeal joint (DIPJ) and, (2) amikacin concentration in the systemic circulation, and (3) regional intravenous pressure. STUDY DESIGN: Randomized cross-over design. ANIMALS: Six adult horses. METHODS: Each horse received IVRLP using 4 perfusate volumes (10, 30, 60 & 120 ml) in random order, after a minimum of 1 week washout. After application of a pneumatic tourniquet, IVRLP with 1 g of amikacin in 0.9% NaCl was performed. Synovial fluid from the RCJ and DIPJ, and systemic and regional venous blood were sampled, and regional blood pressure was measured, immediately before perfusion (time 0), and 15 and 30 minutes after perfusion but before tourniquet release. RESULTS: No difference was observed in the mean amikacin concentration of synovial fluid for the 4 perfusate volumes (P>.09). For all volumes, mean amikacin concentration for DIPJ synovial fluid was higher than for RCJ (P<.0001). The mean amikacin concentration in DIPJ synovial fluid was therapeutic for resistant pathogens using the 10, 60, and 120 mL volumes but the mean amikacin concentration for RCJ synovial fluid was not therapeutic for resistant pathogens with any perfusate volume. All volumes resulted in an immediate increase in mean regional intravascular pressure after perfusion (P<.0001) but was not different across the 4 perfusate volumes. CONCLUSION: Cephalic IVRLP of 1 g of amikacin diluted to a volume of 10-120 mL with 0.9% NaCl will achieve amikacin concentrations therapeutic for resistant pathogens in the synovial fluid from the DIPJ. Concentrations below therapeutic levels for resistant pathogens are reached in the synovial fluid from the RCJ.

Adding adaptable toe stiffness affects energetic efficiency and dynamic behaviors of bipedal walking.

In human walking, toes play an important role in supporting the body and controlling the forward motion. These functions are achieved by muscles and tendons around toe joints. To further understand the importance of toe and how toe muscle functions affect the locomotion, we employ a simple bipedal walking model with compliant joints. The ankle joints and toe joints are modeled as torsional springs and the actuation patterns are similar to that of normal human walking. Experimental results show that adding adaptable compliant toe joints could benefit the stability and energy efficiency. By generating plantar flexion moment after heel-off, the toes contribute to stabilize the body and control the forward motion. In addition, multi-joint foot structure could improve the energy efficiency by reducing the energy consumption of ankle joints. A proper toe actuation pattern could result in a proper toe dorsiflexion and reduce the maximal ankle plantar flexion, leading to a smoother and more efficient locomotion.

Impaired gait function in adults with cerebral palsy is associated with reduced rapid force generation and increased passive stiffness.

OBJECTIVE: It is still not clarified whether spasticity contributes to impairments of gait function. Here we compared biomechanical measures of muscle weakness and stiffness of ankle muscles to impairments of gait function in adults with cerebral palsy (CP). METHODS: Twenty-four adults with CP (mean age 34.3, range 18-57 years) and fifteen healthy age-matched controls were biomechanically measured for passive and reflex-mediated stiffness of the ankle plantarflexors at rest, maximal voluntary plantarflexion and dorsiflexion effort (MVCpf,df) and rate of force development (RFDpf,df). Kinematic analysis of the ankle joint during treadmill walking was obtained by 3-D motion analysis. RESULTS: Passive stiffness was significantly increased in adults with CP compared to controls. Passive stiffness and RFDdf were correlated to reduced toe lift. RFDpf provided the best correlation to push-off velocity, range of movement in the ankle joint and gait speed. Reflex-mediated stiffness was not correlated to any parameters of impaired gait. CONCLUSIONS: Impaired gait function in adults with CP is associated with reduced RFD and increased passive stiffness of ankle muscles. SIGNIFICANCE: These findings suggest that reduced rapid force generation and increased passive stiffness of ankle muscles rather than increased reflex-mediated stiffness (spasticity) likely contributes to impaired gait function in adults with CP.

Hallux abductus interphalangeus in normal feet, early-stage hallux limitus, and hallux valgus.

BACKGROUND: Excessive deviation of the distal phalanx in abduction frequently occurs in advanced stages of hallux rigidus but not in hallux valgus. Therefore, theoretically there should be no significant differences in the hallux interphalangeal angle (HIPA) between individuals with normal feet, those with hallux valgus, and those with mild hallux limitus. The objective of the present study was thus to determine if significant differences in HIPA exist in the early stages of hallux valgus or hallux limitus deformities. METHODS: The hallux interphalangeal angle was measured in three groups of participants: a control group with normal feet (45 participants), a hallux valgus group (49 participants), and a hallux limitus group (48 participants). Both of the pathologies were at an early stage. A dorsoplantar radiograph under weightbearing conditions was taken for each individual, and measurements (HIPA and hallux abductus angle [HAA]) were taken using AutoCAD (Autodesk Inc, San Rafael, California) software. Intergroup comparisons of HIPA, and correlations between HIPA, HAA, and hallux dorsiflexion were calculated. RESULTS: The comparisons revealed no significant differences in the values of HIPA between any of the groups (15.2 ± 5.9 degrees in the control group, 15.5 ± 3.9 degrees in the hallux valgus group, and 16.15 ± 4.3 in the hallux limitus group; P  =  0.634). The Pearson correlation coefficients in particular showed no correlation between hallux dorsiflexion, HAA, and HIPA. CONCLUSIONS: For the study participants, there were similar deviations of the distal phalanx of the hallux with respect to the proximal phalanx in normal feet and in feet with the early stages of the hallux limitus and hallux valgus deformities.

Barefoot stubbing injuries to the great toe in children: a new classification by injury mechanism.

OBJECTIVE: This study was conducted to categorize barefoot stubbing injuries to the great toe in children by injury mechanism to differentiate benign stubbing injuries from more complex injuries necessitating surgery. DESIGN: Prospective clinical series of consecutively treated patients. SETTING: Tertiary university hospital setting. PATIENTS: Forty-one children who had sustained an indirect injury to the great toe during barefoot sports activities between January 2001 and December 2009 were included. INTERVENTION: Conservative or surgical treatment was done according to clinical and radiological findings. MAIN OUTCOME MEASUREMENT: Information regarding injury mechanism was collected from patients, parents, and coaches using skeletal models and assessed by a pediatric orthopedic surgeon. Mechanisms of injury were identified and grouped as follows: hyperabduction-flexion, hyperflexion, hyperabduction-extension, hyperextension, and hyperextension-adduction. RESULTS: Hyperabduction-flexion was the most common mechanism (n = 16), in which interphalangeal joint dislocation and skin disruption was noted in most cases. The second most common mechanism was hyperabduction-extension (n = 14) in which avulsion fracture of the lateral volar condyle of the proximal phalanx was noted in most cases. This avulsion fracture had the worst prognosis after conservative care. CONCLUSIONS: Based on these results, we have created a grading system and treatment protocol for indirect hallux sports injuries in children. Avulsion fracture of the lateral condyle of the proximal phalanx, a result of hyperabduction-extension, is a high-risk sign of nonunion and should be aggressively treated, contrary to previous guidelines. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Supination stress of the great toe for assessing intraoperative correction of hallux valgus.

BACKGROUND: We have devised a new intraoperative technique (supination stress of the great toe) in which correction of hallux valgus and metatarsus primus varus, and reduction of the sesamoids could be simultaneously obtained at hallux valgus surgery. The purpose of this study was to prospectively investigate the efficacy of supination stress for assessing intraoperative correction of hallux valgus. METHODS: Thirty patients (31 feet) with an average age of 59.8 years who had hallux valgus were treated with a proximal metatarsal osteotomy. Supination stress under traction was manually applied to the great toe after release of the distal soft tissues and a proximal metatarsal osteotomy. C-arm fluoroscopy was used to verify correction of hallux valgus and to obtain dorsoplantar non-weightbearing images under supination stress. The dorsoplantar non-weightbearing fluoroscopic images were assessed preoperatively and at the time of intraoperative supination stress. The hallux valgus and intermetatarsal angles were measured. The position of the medial sesamoids was classified with a grading system ranging from I to VII as described by Hardy and Clapham. We defined a grade of IV or less as the normal position of the sesamoids and grade V or greater as lateral displacement of the sesamoids. RESULTS: The average hallux valgus angle was 34.3° preoperatively and 11.9° at the time of intraoperative supination stress. The average intermetatarsal angle was 16.4° preoperatively and 5.5° at the time of intraoperative supination stress (p < 0.0001, p < 0.0001, respectively). At the time of intraoperative supination stress, the hallux valgus angle was 20° or less in all feet, and the intermetatarsal angle was 10° or less in all feet. Preoperatively, all feet were classified as having lateral displacement of the sesamoids. At the time of intraoperative supination stress, all feet were classified as having normal positioning of the sesamoids. CONCLUSIONS: Supination stress of the great toe was an effective maneuver for assessing intraoperative correction of hallux valgus and metatarsus primus varus, and reduction of the sesamoids.

Distal osteotomy of the lateral metatarsals: a series of 72 cases comparing the Weil osteotomy and the DMMO percutaneous osteotomy.

INTRODUCTION: A Weil osteotomy with internal fixation can match the preoperative plan by precisely setting the metatarsal length; however 10 to 30% of patients end up experiencing postoperative stiffness. A percutaneous distal metatarsal mini-invasive osteotomy (DMMO) is a purely extra-articular technique; metatarsal length is set automatically upon weight bearing of the foot. The goal of this study was to compare these two osteotomy techniques when performed on the three or four most lateral metatarsals. HYPOTHESIS: A DMMO will result in better joint motion than a Weil osteotomy. PATIENTS AND METHODS: This was a retrospective, single center, single surgeon study with 72 patients. Group 1 consisted of 39 patients operated by the DMMO technique. Group 2 consisted of 33 patients operated by the standard Weil osteotomy technique. In some cases, a procedure on the first ray (Scarf or fusion) was also performed. The age, gender and procedures on the first ray were comparable for both groups. Patients were evaluated with clinical (AOFAS score) and radiological outcomes (Maestro criteria) at 3 and 12 months minimum follow-up. RESULTS: Sixty-seven patients were seen again with an average follow-up of 14.8 months (range 12-24). The postoperative AOFAS score was comparable in both groups (86.5 and 85.3, respectively). The joint range of motion was comparable in both groups. Static problems (oedema, metatarsalgia, hyperkeratosis and dislocation) were comparable at the last follow-up. The metatarsalgia recurred in four patients from group 1 and five patients from group 2. After 3 months, oedema and metatarsalgia were significantly greater in group 1. Radiological measurements (M1P1angle, M1M2angle and Maestro criteria) were comparable. Metatarsal head recoil was identical between each ray in group 1. At the last follow-up, all the osteotomy sites had achieved union. DISCUSSION AND CONCLUSION: The results of static metatarsalgia treatment were comparable when using a DMMO or Weil osteotomy. However the DMMO had longer postoperative recovery, notably because of oedema. The percutaneous DMMO technique did not improve joint range of motion. LEVEL OF EVIDENCE: III, comparative retrospective study.

A mechanical comparison of equine proximal interphalangeal joint arthrodesis techniques: an axial locking compression plate and two abaxial transarticular cortical screws versus an axial dynamic compression plate and two abaxial transarticular cortical screws.

OBJECTIVES: To compare in vitro monotonic biomechanical properties of an axial 3-hole, 4.5 mm narrow locking compression plate (ELCP) using 5.0 mm locking screws and 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (ELCP-TLS) with an axial 3-hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP-TLS) for equine proximal interphalangeal (PIP) joint arthrodesis. DESIGN: Experimental. ANIMAL POPULATION: Cadaveric adult equine forelimbs (n = 18 pairs). METHODS: For each forelimb pair, 1 PIP joint was stabilized with an axial ELCP using 5.0 mm locking screws and 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion and 1 PIP joint with an axial 3-hole narrow DCP (4.5 mm) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion. Six matching pairs of constructs were tested in single cycle to failure under axial compression, 6 construct pairs were tested for cyclic fatigue under axial compression, and 6 construct pairs were tested in single cycle to failure under torsional loading. Mean values for each fixation method were compared using a paired t-test within each group with statistical significance set at P < .05. RESULTS: Mean yield load, yield stiffness, and failure load under axial compression, single cycle to failure, of the DCP-TLS fixation were significantly greater than those of the LCP-TLS fixation. There was no significant difference between the mean number of cycles to failure in axial compression of the LCP-TLS and the DCP-TLS fixations. Mean yield load, yield stiffness, and failure load under torsion, single cycle to failure, of the LCP-TLS fixation were significantly greater than those of the DCP-TLS fixation. CONCLUSION: The DCP-TLS construct provided significantly greater stability under axial compression in single cycle to failure than the ELCP-TLS construct, the ELCP-TLS construct provided significantly greater stability under torsional loading in single cycle to failure than the DCP-TLS construct, and there was no significant difference in stability between the 2 constructs for cyclic loading under axial compression.