Hindfoot alignment valgus moment arm increases in adult flatfoot with Achilles tendon contracture.

BACKGROUND: Adult acquired flatfoot is often associated with Achilles tendon contracture and may be associated with isolated spring ligament insufficiency without Achilles tendon contracture. We have studied the hypothesis that standing valgus hindfoot alignment moment arm is increased in adult acquired flatfoot with Achilles tendon contracture when compared to adult acquired flatfoot without Achilles tendon contracture. MATERIALS AND METHODS: The standing hindfoot alignment, standing lateral tibial-calcaneal angle, lateral talo-first metatarsal angle, lateral medial cuneiform arch height, and anteroposterior talonavicular coverage angle were measured in 22 patients with a clinical diagnosis of adult acquired flatfoot with one foot with clinical Achilles tendon contracture and one without that diagnosis. We compared the adult acquired flatfoot group to a control group of 15 patients with no foot or ankle deformities or previous foot or ankle surgeries. RESULTS: In patients with flatfoot and Achilles tendon contracture, there was a significantly increased valgus hindfoot alignment, talo-first metatarsal angle, talonavicular coverage angle, tibiocalcaneal angle and a decreased arch height when compared to the control group. In all flatfeet, we found an increased tibiocalcaneal angle. In both flatfoot groups, an increasing tibiocalcaneal angle and an increasing talo-first metatarsal angle was correlated to a decreasing arch height. In adult acquired flatfoot without Achilles tendon contracture diagnosed by clinical exam, an increasing talonavicular coverage angle was correlated to an increasing talo-first metatarsal angle and a decreasing arch height. CONCLUSION: Adults with flatfoot and Achilles tendon contracture have a significantly increased standing hindfoot valgus alignment moment arm and other associated deformities.

A biomechanical analysis of posterior tibial tendon dysfunction, medial displacement calcaneal osteotomy and flexor digitorum longus transfer in adult acquired flat foot.

BACKGROUND: Biomechanical models have been used to study stress in the metatarsals, subtalar motion, lateral column lengthening and subtalar arthroereisis. Posterior tibial tendon dysfunction has been associated with increased loads in the arch of the acquired flat foot. We examine whether a 10 millimeter (mm) medial displacement calcaneal osteotomy and flexor digitorum longus transfer to the navicular reduces these increased loads in the flat foot. METHODS: The response of a normal foot, a foot with posterior tibial tendon dysfunction, and a flat foot to an applied load of 683Newton was analyzed using a multi-segment biomechanical model. The distribution of load on the metatarsals, the moment about each joint, the force on each of the plantar ligaments and the muscle forces were computed. FINDINGS: Posterior tibial tendon dysfunction results in increased load on the medial arch, which may cause the foot to flatten. A 10mm medial displacement calcaneal osteotomy substantially decreases the load on the first metatarsal and the moment at the talo-navicular joint and increases the load on the fifth metatarsal and the calcaneal-cuboid joint. Adding the flexor digitorum longus transfer to the medial displacement calcaneal osteotomy has only a small effect on the flattened foot. INTERPRETATION: Our biomechanical analysis illustrates that when the foot becomes flat, the force on the talo-navicular joint increases substantially from its value for the normal foot, and that medial displacement calcaneal osteotomy can reduce this increased force back toward the value occurring in the normal foot. This study provides a biomechanical rationale for medial displacement calcaneal osteotomy treatments for posterior tibial tendon dysfunction.

A biomechanical analysis of the effect of lateral column lengthening calcaneal osteotomy on the flat foot.

BACKGROUND: Biomechanical models have been used to study the plantar aponeurosis, medial arch height, subtalar motion, medial displacement calcaneal osteotomy, subtalar arthroereisis and the distribution of forces in the normal and flat foot. The objective was to examine the hypothesis that increased load on the medial arch in the adult flat foot can be reduced through a 10mm lateral column lengthening calcaneal osteotomy 10 mm proximal from the calcaneal cuboid joint. METHODS: A three dimensional multisegment biomechanical model was used with anatomical data from a normal foot, a flat foot and a foot corrected with a 10mm lateral column lengthening calcaneal osteotomy. The response of a normal foot, a flat foot and a flat foot with a 10mm lateral column lengthening calcaneal osteotomy to an applied load of 683 N was analyzed using the biomechanical model. Data for the biomechanical model was obtained from a cadaver foot using the direct linear transformation method. Direct linear transformation uses multiple cameras to determine the spatial location of anatomical landmarks. FINDINGS: Load on the first metatarsal increases to 37% body weight in the flat foot compared to 12% for the normal foot and the moment about the talo-navicular joint increases from 5.6 N m to 21.6 N m. Lateral column lengthening shifts the load toward the lateral column, decreasing load on the first metatarsal to 10% and decreasing the moment about the talo-navicular joint to 8.1 N m. INTERPRETATION: The analysis shows that a 10mm lateral column lengthening calcaneal osteotomy reduces the excess force on the medial arch in an adult flat foot and adds biomechanical rationale to this clinical procedure.

Free-flap salvage of soft tissue complications following the lateral approach to the calcaneus.

Soft tissue complications including wound slough and/or infection after lateral foot incisions used to approach the calcaneus are notoriously frequent. Simpler wound management may be possible when early, aggressive treatment is deployed. If definitive coverage has been delayed, local options typically become unreliable. Free tissue transfers may then become the mainstay for limb salvage. Over the past 2 decades in our joint experience in managing such complications referred to us, 8 free flaps were necessary in 7 patients who all had had some form of traumatic injury to the calcaneus. The mean interval from wound compromise to coverage was an exceedingly long 88.1 days (range: 29-166 days). The gracilis muscle was our choice for tissue transfer in every patient as this is a versatile, thin, yet wide-enough muscle with a pedicle length satisfactory to allow reach to nearby recipient sites. There were no flap-related untoward events, with all completely surviving. The anterior tibial/dorsalis pedis axis served as the usual recipient site (87.5%) for microanastomosis. Fixation hardware was retained whenever possible. All limbs were ultimately salvaged to allow reasonable ambulation.

The use of standing lateral tibial-calcaneal angle as a quantitative measurement of Achilles tendon contracture in adult acquired flatfoot.

BACKGROUND: To quantitate the association of Achilles tendon contracture (ATC) with adult acquired flatfoot, the authors hypothesized that the standing lateral tibial-calcaneal angle increases because of ATC. METHODS: The standing lateral tibial-calcaneal angle, talo-first metatarsal angle, lateral talocalcaneal angle, lateral standing medial cuneiform, arch height, and anteroposterior talonavicular coverage angle were measured in 21 patients (25 feet) with clinical diagnoses of ATC and adult acquired flatfoot (AAF) and compared to the same measurements in a control group of 15 patients (30 feet) with no foot deformities or previous foot surgeries. RESULTS: The mean lateral tibial-calcaneal angle in the control group was 64.43 degrees and in the AAF group 71.24 degrees (p < 0.001). The mean lateral talo-first metatarsal angle in the control group was 11.77 degrees, and in the AAF group with ATC it was 25.80 degrees (p < 0.001). The mean arch height in the control group was 17.90 mm and in the AAF group, 8.48 mm (p < 0.001). In the ATC and AAF group an increasing standing lateral tibial-calcaneal angle was correlated with a decreasing lateral talo-calcaneal angle (p = 0.044), and a decreasing arch height was correlated to an increasing lateral talo-first metatarsal angle (p < 0.001). CONCLUSION: Adults with flatfeet and Achilles tendon contracture may have a statistically significant increase in the standing lateral tibial-calcaneal angle. This angle may be a reproducible measure of ATC. An increase in the standing lateral tibial-calcaneal angle may confirm and quantitate the clinical diagnosis of Achilles tendon contracture. Further studies with more patients are needed.

Radiographic comparison of standing medial cuneiform arch height in adults with and without acquired flatfoot deformity.

BACKGROUND: Adult acquired flatfoot (AAF) is characterized by decreased arch height, talar depression, medial arch depression and elongation, and forefoot abduction. We have measured standing arch height in AAF patients and in a control group of patients using the standing lateral medial cuneiform arch height radiographic measurement. METHODS: Fifteen (25 feet) patients were selected with the clinical diagnosis of symptomatic AAF with no secondary diagnoses. A control group consisted of 36 (72 feet) patients with no foot deformities or prior foot surgeries. Arch height was measured in millimeters using the standing medial cuneiform height on the lateral radiographic view. RESULTS: The mean standing medial cuneiform arch height in the control group was 18.38 mm. The mean arch height in the AAF group was 11.04 mm (p < 0.001). There were no differences between right and left feet in the control group or symptomatic and contralateral feet in the AAF group. Body mass index (BMI) in the control group was 26.17 and in the AAF 33.74. (p = 0.007). CONCLUSION: These data provide a control value for the arch height using the medial cuneiform as reference. The decrease in arch height is a strong indicator of AAF. A study with larger numbers of patients is necessary.

A biomechanical model of the effect of subtalar arthroereisis on the adult flexible flat foot.

OBJECTIVE: The hypothesis tested was that the increased load on the medial arch in the adult flat foot can be reduced through a 6 mm subtalar arthroereisis. DESIGN: A three-dimensional multisegment biomechanical model was used in conjunction with experimental data and data from the literature. BACKGROUND: Biomechanical models have been used to study the plantar fascia, medial arch height, subtalar motion, medial displacement calcaneal osteotomy and distribution of forces in the foot. METHODS: Responses of a normal foot, a flat foot, and a flat foot with a subtalar arthroereisis to an applied load of 683 N were analyzed and the distribution of support among the metatarsal heads and the moment about various joints were computed. RESULTS: The flattened foot results in an increase in the load on the head of the first metatarsal from 10% to 24% of the body weight, and an increase in the moment about the talo-navicular joint from 3.4 to 11.9 Nm. Insertion of a 6 mm cylinder into the sinus tarsi, subtalar arthroereisis, results in a shift of the load back toward the lateral column, decreasing the load on the first metatarsal to 6% of the body weight and decreasing the moment about the talo-navicular joint to 6.0 Nm. CONCLUSIONS: Our analysis indicates that a 6 mm subtalar arthroereisis in an adult flat foot model decreases the load on the medial arch.

The accessory extensor tendon of the first metatarsophalangeal joint.

The accessory extensor tendon of the first metatarsophalangeal joint (1st MTPJ) was evaluated in 32 cadaver feet. Eighty-one percent of feet possessed an accessory tendon to the 1st MTPJ. Of those feet possessing an accessory tendon to the 1st MTPJ, approximately 92% originated from the extensor hallucis longus muscle-tendon unit, while approximately 8% originated from the tibialis anterior muscle-tendon unit. All accessory tendons inserted onto the dorsal/dorsomedial capsule of the 1st MTPJ. Accessory tendons were found to be bilateral in the majority (87.5%) of specimens. Differences in sex distribution of the accessory tendon of the 1st MTPJ were not statistically significant. The difference in distribution of an accessory tendon to the 1st MTPJ in those feet that demonstrated clinical hallux valgus versus those that did not demonstrate hallux valgus was not statistically significant (p = 1.0000, respectively, Fisher's exact test). This tendon is unique to the human foot (lacking in primates) and is a fairly constant structure (80%). The data presented do not lend support for the accessory tendon of the 1st MTPJ to play a role in the development of hallux valgus. At the present time, the role of this accessory tendon on the biomechanics of the 1st MTPJ remains unknown.