Introduction: The first metatarsal: it's importance in the human foot

The Application of Morton's Observations to Contemporary Treatment of Foot Dysfunction

Understanding the evolution of the human foot from a flexible grasping structure to one that is designed for upright posture and locomotion is paramount to treating patients with foot pain and dysfunction. Almost 100 years ago, Dudley Morton observed that certain retained atavistic traits are responsible for pathologic breakdown of the modern foot. Cadaveric research under the direction of Jeffrey Christensen provided evidence that lengthening the gastrocnemius and stabilizing the medial column helped correct the faulty biomechanics associated with Morton foot and corroborated Hansen's blueprint for reconstructive surgery of the foot and ankle.

Inferring the mobility of a middle Upper Paleolithic female skeleton from Caviglione (Liguria, Italy): Impact of trauma and mountainous terrain

Mobility and territory occupation, the participation of injured individuals in group activities, and the role of women in early human groups are crucial issues in human evolution. Previously, a biomechanical study showed evidence of several traumas to the upper limb of the well-preserved middle Upper Paleolithic (UP) female skeleton from Caviglione (Caviglione 1, Liguria, Italy) but did not characterize their impact on locomotor behavior. Furthermore, mobility in the European UP context is thoroughly documented in males but not in females. Therefore, we examined whether this trauma-affected female skeleton shows bone adaptation to high mobility, as expected in UP groups, and to frequent foot eversion and inversion, as expected, given the mountainous area in which it was discovered. This study investigated the structural properties of the femur, tibia, fibula, and first metatarsal to infer the mobility level and pattern of Caviglione 1. We analyzed the diaphyseal 'shape', robusticity, fibular cortical distribution, and relative robusticity (fibula versus tibia). No substantial findings were derived from the first metatarsal. The fibular cortical distribution can discriminate 'active' (nomadic or settled) and recent sedentary human groups; these findings indicated Caviglione 1 belonged to the former. Interestingly, compared with ancient and recent sedentary humans and some UP individuals, Caviglione 1 had femurs with strong relative anteroposterior rigidity and robust tibias and fibulas reflecting an adaptation to extremely high levels of mobility. The very high relative fibular robusticity of Caviglione 1, higher than that of Middle UP males, is consistent with bone adaptation to frequent travel through mountainous terrain. Such fibular robusticity may also be a consequence of imbalance, due to upper limb traumas, when traveling downhill. These findings indicate that injured individuals may have participated in subsistence activities in past populations and describe an UP female with bone adaptations to habitual high mobility, notably in mountainous terrain.

First ray alignment in Lapidus arthrodesis - Effect on plantar pressure distribution and the occurrence of metatarsalgia

BACKGROUND

Lapidus arthrodesis is an established treatment option for severe hallux valgus deformity especially in patients suffering from instability of the first tarsometatarsal joint. Surgery related metatarsalgia is known to be associated with persistent elevation of the first ray after realignment surgery. Nevertheless, detailed information on ideal positioning of the first ray in Lapidus surgery is missing so far. This study was designed to determine any correlations between radiographic and pedobarographic outcome following the Lapidus procedure with regard to clinical outcome and the occurrence of metatarsalgia.

METHODS

Thirty feet (28 patients) after Lapidus surgery were available for follow-up at 42.5±21.0 months. All subjects had radiographic and pedobarographic evaluation of the operated foot and patient satisfaction was recorded using questionnaires.

RESULTS

Metatarsalgia was associated with a poorer outcome in FADI and AOFAS scores (p<0.005). A lateral shift of plantar pressure distribution to the third metatarsal head in these cases could be observed. Although Lapidus surgery resulted in significant shortening of the first metatarsal, no correlation to the occurrence of metatarsalgia was detectable. Likewise, axial plane malalignment showed no influence, whereas elevation of the first ray was highly correlated to surgery related metatarsalgia (p=0.007). Subjects suffering from metatarsalgia had a higher BMI (body mass index), but its effect on metatarsalgia turned out not to be significant (p=0.090).

CONCLUSION

In Lapidus surgery realignment of the first metatarsal in the sagittal plane seems to be decisive for good clinical outcome. Failing to plantarflex the arthrodesis resulted in a lateral shift of plantar loading with overload of the lesser metatarsals and the occurrence of metatarsalgia.

Effects of the lapidus arthrodesis and chevron bunionectomy on plantar forefoot pressures

Hallux valgus with or without first ray insufficiency has been strongly implicated as a contributing factor in lesser metatarsal overload. The principle goals of a bunionectomy are to relieve the pain, correct the deformity, and restore first metatarsophalangeal joint congruity. Until now, little evidence has been available to assess the effects of bunionectomy procedures on forefoot pressure. The primary aim of the present prospective study was to evaluate the preoperative and postoperative plantar pressures after 2 specific bunionectomies: the chevron bunionectomy and Lapidus arthrodesis. A total of 68 subjects, 34 in each group, were included for radiographic and pedographic evaluation. Both procedures demonstrated radiographic improvements in the mean intermetatarsal and hallux abductus angles. The mean hallux plantar pressure decreased significantly in both procedure groups (p < .001). However, Lapidus group exhibited an increase in the mean fifth metatarsal head plantar pressure (p = .008) and pressure under the fifth metatarsal as a percentage of the total forefoot pressure (p = .01). Furthermore, the pressure under the second metatarsal as a percentage of the total forefoot pressure decreased significantly (p = .01). This study suggests that the Lapidus arthrodesis and chevron bunionectomy both provide correction for hallux valgus deformity, but when comparing forefoot load sharing pressures, the Lapidus arthrodesis appeared to have greater influence on the load sharing distribution of forefoot pressure than did the bunionectomy employing the chevron osteotomy.

Normal genetic variation of the human foot: Part 2: Population variance, epigenetic mechanisms, and developmental constraint in function

Congenital deformities of the foot have been reported to correlate with regulatory epigenetic mechanisms that are also responsible for the timing and sequencing of developmental growth of the lower limb. Developmental variance of normal morphologic features has also been shown to vary between populations despite the retention of human foot characteristics. The molecular evidence for genetically controlled expressions of common evolved physical features is highly suggestive of regulatory control mechanisms that act together with developmental constraints to homogenize the retained functional characteristics of the foot. Genetic variance in morphologic features and functional plasticity when linked to morphometric change during gait may prove influential in clarifying kinematic and kinetic relationships.

A clinically applicable six-segmented foot model

We describe a multi-segmented foot model comprising lower leg, rearfoot, midfoot, lateral forefoot, medial forefoot, and hallux for routine use in a clinical setting. The Ghent Foot Model describes the kinematic patterns of functional units of the foot, especially the midfoot, to investigate patient populations where midfoot deformation or dysfunction is an important feature, for example, rheumatoid arthritis patients. Data were obtained from surface markers by a 6 camera motion capture system at 500 Hz. Ten healthy subjects walked barefoot along a 12 m walkway at self-selected speed. Joint angles (rearfoot to shank, midfoot to rearfoot, lateral and medial forefoot to midfoot, and hallux to medial forefoot) in the sagittal, frontal, and transverse plane are reported according to anatomically based reference frames. These angles were calculated and reported during the foot rollover phases in stance, detected by synchronized plantar pressure measurements. Repeated measurements of each subject revealed low intra-subject variability, varying between 0.7° and 2.3° for the minimum values, between 0.5° and 2.1° for the maximum values, and between 0.8° and 5.8° for the ROM. The described movement patterns were repeatable and consistent with biomechanical and clinical knowledge. As such, the Ghent Foot model permits intersegment, in vivo motion measurement of the foot, which is crucial for both clinical and research applications.