Morphometric study of the human metatarsals and phalanges

Feline Skeletal Reference Guide: A Cadaveric Radiographic Measurement on Lower Limb Extremities

OBJECTIVE

 The aim of this study was to create a feline reference database for the length, width and slenderness (length to width ratio) of metacarpal and metatarsal bones, radius and tibia.

STUDY DESIGN

 Radiographs of the radius, tibia, metacarpus and metatarsus were performed in domestic short hair cat cadavers (n = 40). Length and width of the aforementioned bones were measured in mature domestic shorthair cats and bone slenderness (length/width) and index ratios calculated.

RESULTS

 A significant skeletal sex dimorphism exists in cats, with bones of the metacarpus, metatarsus, radius and tibia generally longer and wider in male cats compared with female cats, with differences frequently significant. The most significant difference was identified for the width of Mc5 (p = 0.0008) and the length and width of Mt5 (p = 0.0005). Index ratios for length and width of radius to metacarpal bones, and tibia to metatarsal bones, were not significantly different between male and female cats, except for Mc5. The index ratio for Mc5 was significantly higher in male cats (p = 0.002).

CONCLUSION

 The present study provides insights into the normal length and width of distal forelimb and hind limb bones as well as bone index ratios in mature domestic shorthair cats. Using this information, it is now possible to quantitatively assess the relationship between these bones in domestic cats using radiography. This will assist not only with the diagnosis and categorization of skeletal abnormalities but can also guide surgical interventions of metacarpal and metatarsal bone fractures.

Radiological Biometric Study of Metatarsals and Phalanges

Introduction

Several diseases affect the forefoot bones. Relative dimensions of the forefoot bones are important considerations for preoperative and postoperative assessment of surgeries. The choice of a particular surgery over another can also be made if the surgeon knows the length to which a bone needs to be lengthened or shortened in comparison to other bones of the forefoot.

Aim

To measure the dimensions of the metatarsals and phalanges on standardized radiographs and to determine possible correlations amongst them.

Materials and Methods

A cross-sectional prospective study was conducted on 60 volunteer participants of either sex. The dimensions of metatarsals and phalanges were measured on standardized radiographs of both feet in 60 healthy adults. The mean, range and standard deviation were calculated. Correlation analysis was done to assess the association between the variables.

Results

The first metatarsal was the shortest (56.42±4.41 mm in males and 50.09±3.06 mm in females) and widest of all metatarsals (13.7±1.00 mm in males and 11.7±0.91 mm in females). The first proximal phalanx was the longest (28.0±2.40 mm in males and 25.8±2.21 mm in females) and the fifth distal phalanx (5.2±1.33 mm in males and 4.4±1.03 mm in females) was the shortest of all phalanges. A strong correlation (p<0.001) exists amongst the lengths of metatarsals, proximal phalanges and middle phalanges, within their own groups.

Conclusion

Correlation of the lengths and widths of the forefoot bones amongst themselves and between types can be calculated mathematically utilising standardized radiographs. This helps in assessment of forefoot disorders, choose an appropriate surgical technique and postoperative evaluation.

Screwless scarf osteotomy for hallux valgus: Evaluation of radiologic correction

BACKGROUND

The scarf osteotomy is a standard procedure to correct hallux valgus. Recent modifications in the technique allow for important translations of the bone fragments without the need for screw fixation. We performed the first prospective analysis of radiographic parameters after a screwless scarf osteotomy. Prospective study of pre- and postoperative standing radiographs of the feet let us quantify angle reduction and shortening, lengthening or lowering of the first metatarsal.

METHODS

100 patients undergoing a screwless scarf osteotomy were evaluated radiographically before and after surgery. The 1-2 IM angle, HVA, length of the first metatarsal, protrusion length and height of the first metatarsal head were measured.

RESULTS

The mean 1-2 IM angle was reduced significantly, to a normal range. The mean reduction of the first metatarsal length and protrusion length was 0.3 and 0.14cm respectively. The metatarsal head was lowered 0.3cm on average.

CONCLUSIONS

A minimal mean reduction of the first metatarsal length was observed, but it is possible to lengthen the first metatarsal if necessary. In 23% of cases, an increase of protrusion length was obtained. The screwless scarf osteotomy results in a good correction of the 1-2 IM angle and HVA. If necessary, plantarisation of the first metatarsal head could be obtained. Secondary displacement was seen in 1 patient.

LEVEL OF EVIDENCE

IIa, prospective controlled trial.

Metatarsal fractures: A review and current concepts

Metatarsal fractures represent a significant proportion of foot injuries. Various patterns of metatarsal injuries exist and the resultant impact on function and quality of life is not negligible. This in fact reflected the attention given to these fractures in the medical literature. Conventionally, a complete clinical and radiological assessment is needed in order to guide management and tailor treatment options to the clinical and functional needs of the individual metatarsal fracture. This article provides a thorough review of all metatarsal fractures; it examines the latest literature especially in relation to management of distinct types of metatarsal fractures. Special attention is given to the first metatarsal due to its important implication in stable functionality of the first ray and foot. In relation to the higher incidence of fifth metatarsal fractures this article provides a broader review of their management.

The Influence of the Length of the First Metatarsal on the Risk of Reulceration in the Feet of Patients With Diabetes

Our aim was to identify the optimal diagnostic cutoff point on the scale of protrusion measurements of the first metatarsal (M1) to predict the probability of reulceration after metatarsal head resection in patients with diabetes mellitus. We conducted a prospective study of patients with diabetes who underwent resection of at least 1 metatarsal head in our department. After surgery, we measured the difference in length (protrusion) between the M1 and the longest of the 4 lesser metatarsals by radiographic view. The patients were divided into those in whom the M1 was the longest of the 5 metatarsals (group 1) and patients in whom at least one of the lesser metatarsals was longer than the M1 (group 2). They were followed-up for 12 months and were assessed for reulceration. Ninety-one patients were included in the present study: 43 (47%) in group 1 and 48 (53%) in group 2. In group 1, the longer the protrusion of M1 was, the higher the probability for reulceration ( P < .001, 95% confidence interval = 0.813-0.997). In group 2, the shorter the protrusion of M1, the higher the probability for reulceration ( P = .002, 95% confidence interval = 0.628-0.905). The optimal cutoff point for group 1 was 11 mm (sensitivity = 84.6%, specificity = 86.7%) for the probability of reulceration. In group 2, it was −7 mm (sensitivity = 81.8%, specificity = 65.4%). These results suggest that M1 protrusion is an optimum prognostic indicator for reulceration and could be recommended for detecting patients at risk of reulceration after surgery.

Fundamental ratios and logarithmic periodicity in human limb bones

Fundamental mathematical relationships are widespread in biology yet there is little information on this topic with regard to human limb bone lengths and none related to human limb bone volumes. Forty-six sets of ipsilateral upper and lower limb long bones and third digit short bones were imaged by computed tomography. Maximum bone lengths were measured manually and individual bone volumes calculated from computed tomography images using a stereologic method. Length ratios of femur : tibia and humerus : ulna were remarkably similar (1.21 and 1.22, respectively) and varied little (<7%) between individuals. The volume ratio of femur : tibia was approximately half that of humerus : ulna (1.58 and 3.28, respectively; P < 0.0001). Lower limb bone volume ratios varied much more than upper limb ratios. The relationship between bone length and volume was found to be well described by power laws, with R(2) values ranging from 0.983 to 0.995. The most striking finding was a logarithmic periodicity in bone length moving from distal to proximal up the limb (upper limb λ = 0.72, lower limb λ = 0.93). These novel data suggest that human limb bone lengths and volumes follow fundamental and highly conserved mathematical relationships, which may contribute to our understanding of normal and disordered growth, stature estimation, and biomechanics.

Ankle joint mechanics and foot proportions differ between human sprinters and non-sprinters

Recent studies of sprinters and distance runners have suggested that variations in human foot proportions and plantarflexor muscle moment arm correspond to the level of sprint performance or running economy. Less clear, however, is whether differences in muscle moment arm are mediated by altered tendon paths or by variation in the centre of ankle joint rotation. Previous measurements of these differences have relied upon assumed joint centres and measurements of bone geometry made externally, such that they would be affected by the thickness of the overlying soft tissue. Using magnetic resonance imaging, we found that trained sprinters have shorter plantarflexor moment arms (p = 0.011) and longer forefoot bones (p = 0.019) than non-sprinters. The shorter moment arms of sprinters are attributable to differences in the location of the centre of rotation (p < 0.001) rather than to differences in the path of the Achilles tendon. A simple computer model suggests that increasing the ratio of forefoot to rearfoot length permits more plantarflexor muscle work during plantarflexion that occurs at rates expected during the acceleration phase following the sprint start.

Definition of coordinate system for three-dimensional data analysis in the foot and ankle

BACKGROUND

Three-dimensional data is required to have advanced knowledge of foot and ankle kinematics and morphology. However, studies have been difficult to compare due to a lack of a common coordinate system. Therefore, we present a means to define a coordinate frame in the foot and ankle and its clinical application.

MATERIALS AND METHODS

We carried out ten CT scans in anatomically normal feet and segmented them in a general purpose segmentation program for grey value images. 3D binary formatted stereolithography files were then create and imported to a shape analysis program for biomechanics which was used to define a coordinate frame and carry out morphological analysis of the forefoot.

RESULTS

The coordinate frame had axes standard deviations of 2.36 which are comparable to axes variability of other joint coordinate systems. We showed a strong correlation between the lengths of the metatarsals within and between the columns of the foot and also among the lesser metatarsal lengths.

CONCLUSION

We present a reproducible method for construction of a coordinate system for the foot and ankle with low axes variability.

CLINICAL RELEVANCE

To conduct meaningful comparison between multiple subjects the coordinate system must be constant. This system enables such comparison and therefore will aid morphological data collection and improve preoperative planning accuracy.