A critical analysis of Dudley Morton's concept of disordered foot function.

The name Morton is associated with a foot structure characterized by a short first metatarsal in comparison with the adjacent second metatarsal. Dudley Morton is credited with recognizing a short first metatarsal as being a primary defect of the foot. Morton, an anatomist, approached his observation from an evolutionary perspective. His theory of disordered foot function was based on the premise that human alignment centered on an "axis of leverage" and around an "axis of balance." Morton concluded that the presence of a short first metatarsal was compounded when the first metatarsal segment was hypermobile. Shortness and hypermobility diminished the capacity of the first metatarsal segment to carry weight, allowed pronation during activity, and led to an overload of the central metatarsals. The term Morton Foot sprang from his teachings. The extensive writings of Morton are commonly cited even today. This study compares Morton's teachings with research published during the last 70 years, which either supports or refutes his claims.

Criterion-related validity of a clinical measure of dorsal first ray mobility.

STUDY DESIGN: Test-retest methodological design using a sample of convenience. OBJECTIVE: To determine the criterion-related validity and the reliability of measuring first ray mobility with a ruler. BACKGROUND: Studies have questioned the accuracy of assessing first ray mobility by manual examination. Use of a ruler and adherence to strict guidelines in positioning of the patient may improve the measure. This study investigates the validity, and the intrarater and interrater reliability of measuring dorsal first ray mobility with a ruler while following recent recommendations to standardize the position of measurement. A valid and reliable mechanical device designed to measure first ray mobility was used as the validation criterion of measurement. METHODS: Three clinicians performed ruler measurement of dorsal mobility on 14 subjects. A separate examiner measured dorsal mobility with the mechanical device. Intraclass correlation coefficients (ICCs) and standard error of measurements (SEMs) were computed to quantify the intrarater reliability of both testing procedures and the interrater reliability of the ruler measurement. ICCs of agreement were also computed to determine the concurrent validity of the ruler measurement for each clinician. RESULTS: Mechanical device intrarater reliability ICC was 0.98 (SEM = 0.15 mm). Ruler intrarater ICCs were equal or less than -0.06 (SEMs = 1.1 mm); ruler interrater ICC was 0.05 (SEM = 1.2 mm). The ICCs of agreement between the mechanical device and ruler method ranged from -0.44 to 0.06. CONCLUSION: The ruler method of testing demonstrates poor reliability and validity as a clinical measure.

Dorsal mobility and first ray stiffness in patients with diabetes mellitus.

BACKGROUND: Limited joint mobility in diabetic patients has been identified as a risk factor in the development of plantar ulcers. We examined dorsal mobility and passive first ray stiffness in patients with diabetes and investigated the relationship between first ray mobility and ankle joint dorsiflexion. METHODS: Forty individuals were studied: 20 with diabetes (mean estimated duration of 16 +/- 10 years) and 20 matched controls. Dorsal first ray mobility was measured using a mechanical device. Force-vs-dorsal mobility displacement values were collected at 10 N increments to a load limit of 55 N. Ankle joint dorsiflexion motion was measured with a goniometer. The "prayer sign," a clinical indicator of limited joint mobility, was evaluated in each patient. Subjects were separated into the two groups for data analysis. RESULTS: Patients in the diabetic group had more stiffness and less dorsal first ray mobility than the control group (p <.05). In particular, patients with a positive prayer sign had significant first ray stiffness (p <.05). Patients with diabetes also had less ankle dorsiflexion (p <.05). CONCLUSION: Patients with diabetes have more stiffness and less first ray mobility and less ankle dorsiflexion than those without diabetes. The presence of a positive prayer sign correlates with stiffness and loss of first ray mobility. Soft-tissue stiffness may contribute to the development of foot ulcers in diabetic patients with neuropathy.

Dorsal first ray mobility in women athletes with a history of stress fracture of the second or third metatarsal.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: To examine the amount of dorsal first ray mobility in subjects having a history of stress fracture of the second or third metatarsal as compared to control subjects, and to test the influence of navicular drop, length of the first ray, and generalized joint laxity on the measure of dorsal mobility. BACKGROUND: [corrected] Instability of the first ray may cause the lesser metatarsals to carry greater weight and contribute to the incidence of metatarsal stress fracture. Stability of the first ray is believed to be compromised when subtalar joint pronation continues into late stance, the first metatarsal is short, or an individual has generalized joint laxity. To date, no research has assessed the relationship of these etiological factors to the measure of first ray mobility. METHODS AND MEASURES: Fifteen women athletes having a history of a second or third metatarsal stress fracture were matched by age, body mass, and sport activity to women athletes without fracture. Dorsal first ray mobility was quantified by a device using a standard load of 55 N. Change in vertical height of the navicular during stance was the measure of foot pronation. Relative length of the first ray navicular segment compared to the length of the second ray navicular segment was measured by caliper. Generalized joint laxity was evaluated using the Beighton 9-point scale. Within-day repeated measures assessed reliability. Differences between groups were determined by independent t test. Multiple polynomial regression analysis assessed the relationship between dorsal mobility and navicular drop, length of the first ray, and joint laxity. RESULTS: Interrater reliability coefficients ranged from 0.36 for metatarsal length to 0.71 for navicular drop. The intrarater reliability coefficient for dorsal first ray mobility was 0.93. Dorsal first ray mobility was not significantly different between the 2 groups. With regression analysis, the Beighton score was the only variable retained as a significant predictor of dorsal mobility (R2 = 0.24). CONCLUSION: Results do not support the theory that describes the unstable first ray as a common cause of metatarsal stress fracture. In addition, this investigation found generalized joint laxity to be a significant predictor of dorsal first ray mobility.