A Tissue Dielectric Constant Evaluation of Knee Edema: A Retrospective Intra-rater Reliability and Association Study of Repeated Measures.

BACKGROUND: This research compared the reliability and association of tissue dielectric constant (TDC) measures of knee edema to circumferential measurements of knee girth recorded as part of a physical therapy examination. METHODS: Twenty adults having observable unilateral knee edema were enrolled. A single examiner measured edematous knee swelling with a TDC device and a tape measure across two visits. The presence of edema was recorded as a positive number in reporting side-to-side differences and a positive percentage in documenting change over time. Intra-rater reliability of the measures was assessed with an intra-class correlation coefficient (ICC). Percent change in edema was evaluated independently for both methods using a paired t-test, and the association between measures was assessed by a Pearson's statistic. RESULTS: Both measures were reliable (ICC ≥ 0.81), and both detected a significant percentage decrease (p < 0.05) in edema across visits. The TDC measure changed by 8.3%, an amount nearly four times larger compared to knee girth (2.4%). The subsequent follow-up comparison revealed an inverse relationship (p = 0.049; r = -0.44) between the two percent change measurements of edema. CONCLUSION: The two methods capture different physical attributes of edema. The TDC records the water content of the tissue, while the use of a tape measure records circumferential limb girth. The TDC measurement was reliable and more responsive in detecting a percentage decrease in knee edema in comparison to a circumferential measure of knee girth. The TDC method may have wider use in directly measuring edema in other tissue structures and regions of the body.

An Operational Definition of First Ray Hypermobility.

BACKGROUND: The first ray (metatarsocuneiform) behaves as a load-bearing strut in supporting weight. Due to its functional importance, stress-testing techniques are used to assess the stability of the first ray and objectify evidence of hypermobility. The test and measurement of first ray hypermobility (FRH) is of interest to clinicians and researchers. The condition itself, however, has proven elusive to diagnose. This article defines FRH for the purpose of improving the consistency by which the diagnosis is made. Currently, the lack of a consensus definition prevents research from determining the incidence rates and prevalence of FRH, a commonly reported medical condition. THE DEFINITION: Symptomatic FRH presents as dorsal displacement that measures greater than 8 mm, accompanied with signs and symptoms consistent with loading insufficiency of the first ray. The operational definition is objective and if adopted across health care professions, the criterion could become the standard for identifying FRH in patients and research participants. LEVEL OF EVIDENCE: Level V, expert opinion.

Measurement of Dorsal First Ray Mobility: A Topical Historical Review and Commentary.

Despite evidence that instability of the first ray (first metatarsal and medial cuneiform) alters the loading mechanics of the foot, surprisingly few studies have linked the condition with disorders of the foot. A factor limiting this research is the difficulty associated with measuring first ray mobility (FRM). To quantify dorsal FRM, clinicians and researchers have devised a variety of methods that impose a dorsally directed load, and record displacement. The methods include manual examination, radiographs, mechanical devices, and handheld rulers. Since different methods yield different results; each of these methods is worthy of scrutiny. This article reviews the methods used to quantify dorsal FRM and offers commentary on how the testing procedures could be standardized. The measurement of dorsal FRM informs surgical decisions, orthotic prescriptions, and research design strategies mostly as it pertains to the identification and treatment of first ray hypermobility. This review found sufficient support to recommend continued use of radiographs and mechanical devices for quantifying dorsal displacement, whereas measurements acquired with handheld rulers are prone to the same subjective error attributed to manual examination procedures. Since measures made with radiographs and existing mechanical devices have their own drawbacks, the commentary recommends ideas for standardizing the testing procedure and calls for the development of a next-generation device to measure dorsal FRM. This future device could be modeled after arthrometers that exist and are used to quantify stability at the knee and ankle. Level of Evidence: Level V, expert opinion.

An Imaged-Based Three-Dimensional Study of First Metatarsal Protrusion Distance in Women with and Without Hallux Valgus.

BACKGROUND: First metatarsal protrusion distance (MPD) has been commonly studied as a characteristic of hallux valgus deformity. To date, the majority of investigations have used radiographic methods, with most reporting first metatarsal (ray) protrusion to be associated with deformity. As an alternative, this study used a three-dimensional (3-D) image acquisition and data analysis method to quantify MPD. METHODS: Magnetic resonance images were acquired in weightbearing on 29 women (19 with hallux valgus; 10 controls). After the 3-D images were reconstructed into virtual bone models, two examiners measured MPD in relation to the navicular. In addition to a reliability analysis, a t test assessed for group differences in demographics, foot posture (hallux valgus, intermetatarsal angles), and MPD. RESULTS: Group demographics were not different, while measures of hallux valgus and intermetatarsal angles were different ( P < 0.01) between groups. The measurement of MPD was highly reliable (ICC [Formula: see text] 0.99; SEM [Formula: see text] 0.78 mm). Metatarsal protrusion averaged approximately -2.0 mm in both groups. There was no statistical group difference ( P = 0.89) in MPD. CONCLUSIONS: The reconstructed image datasets captured the 3-D spatial relationship of the anatomy. Measurements of MPD were reliable. The first ray measured 2 mm shorter than the second ray in both the hallux valgus and control groups. Though unexpected, this result may prompt future study of the pathokinematics associated with hallux valgus that include the quantification of metatarsal protrusion with 3-D methods, instead of relying solely on single-plane radiograph reports.

Treatment of Progressive First Metatarsophalangeal Hallux Valgus Deformity: A Biomechanically Based Muscle-Strengthening Approach.

Synopsis Hallux valgus is a progressive deformity of the first metatarsophalangeal joint that changes the anatomy and biomechanics of the foot. To date, surgery is the only treatment to correct this deformity, though the recurrence rate is as high as 15%. This clinical commentary provides instruction in a strengthening approach for treatment of hallux valgus deformity, by addressing the moment actions of 5 muscles identified as having the ability to counter the hallux valgus process. Unlike surgery, muscle strengthening does not correct the deformity, but, instead, reduces the pain and associated gait impairments that affect the mobility of people who live with the disorder. This review is organized in 4 parts. Part 1 defines the terms of foot motion and posture. Part 2 details the anatomy and biomechanics, and describes how the foot is changed with deformity. Part 3 details the muscles targeted for strengthening; the intrinsics being the abductor hallucis, adductor hallucis, and the flexor hallucis brevis; the extrinsics being the tibialis posterior and fibularis longus. Part 4 instructs the exercise and reviews the related literature. Instructions are given for the short-foot, the toe-spread-out, and the heel-raise exercises. The routine may be performed by almost anyone at home and may be adopted into physical therapist practice, with intent to strengthen the foot muscles as an adjunct to almost any protocol of care, but especially for the treatment of hallux valgus deformity. J Orthop Sports Phys Ther 2016;46(7):596-605. Epub 6 Jun 2016. doi:10.2519/jospt.2016.6704.

Comparison of 2D-3D Measurements of Hallux and First Ray Sagittal Motion in Patients With and Without Hallux Valgus.

BACKGROUND: Clinicians base treatment decisions on measures of hallux and first ray motion in the management of first metatarsophalangeal joint disorders. Women account for a majority of the patients. This study assessed the reliability of a 2D approach for the measurements of sagittal motion, and compared the result to a Cardan (3D) angle criterion standard and evaluated how hallux valgus (bunion) deformity affected the comparisons. METHODS: Twenty-nine women (controls n = 10; bunion n = 19) were examined using a retrospective repeated measures design. Weightbearing magnetic resonance (MR) images were acquired to replicate the position of the foot during the stance phase of gait. The images were reconstructed into virtual bone models using computer processes, whereby measures of hallux and first ray motion were represented by 2D and 3D methods of measurement. An examiner measured 2D motion on the image data sets using a goniometer, and reliability was assessed. The 3D Cardan angle result was derived from a matrix calculation. The 2D-3D comparison of measurements was evaluated with an analysis of variance (ANOVA) model across gait conditions, run separate for groups. RESULTS: The 2D measurement was reliable (ICC ≥ 0.98, SEM ≤ 0.89 degrees). There was no method-by-condition interaction (F ≤ 1.37, P ≥ .25) between variables. No significant difference was detected between the 2D-3D measurements in the control group (F ≤ 1.24, P ≥ .30), but the measurements were statistically different (F ≥ 4.46, P ≤ .049) in the bunion group. CONCLUSION: This study described a reliable 2D approach for measuring hallux and first ray sagittal motion from weightbearing images. The 2D measurements were comparable to a Cardan angle component motion result in controls, but not in women with bunion. CLINICAL RELEVANCE: Joint motion measurements may augment clinical decision making. These results suggest that a 2D image-based approach may be adequate to estimate hallux and first ray sagittal motion, although bunion deformity creates out-of-plane motions that may require 3D methods to accurately quantify. Further clinical study is required to assess the differences in clinical outcomes between measurement techniques.

Cardan angle rotation sequence effects on first-metatarsophalangeal joint kinematics: implications for measuring hallux valgus deformity.

BACKGROUND: There currently are no recommended standards for reporting kinematics of the first-metatarsophalangeal joint. This study compared 2 different rotation sequences of Cardan angles, with implications for understanding the measurement of hallux valgus deformity. METHODS: Thirty-one women (19 hallux valgus; 12 controls) participated. All were scanned in an open-upright magnetic resonance scanner, their foot posed to simulate the gait conditions of midstance, heel-off, and terminal stance. Using computer processes, selected tarsals were reconstructed into virtual bone models and embedded with principal-axes coordinate systems, from which the rotation matrix between the hallux and first metatarsal was decomposed into Cardan angles. Joint angles were then compared using a within factors (rotation sequence and gait condition) repeated-measures analysis of variance (ANOVA). RESULTS: Only the transverse plane-first sequence consistently output incremental increases of dorsiflexion and abduction across gait events in both groups. There was an interaction (F ≥ 25.1; p < 0.001). Follow-up comparisons revealed angles were different (p < 0.05) at terminal stance. CONCLUSIONS: Different rotation sequences yield different results. Extracting the first rotation in the transverse plane allows for the resting alignment of the hallux to deviate from the sagittal plane. Therefore, representing first-metatarsophalangeal joint kinematics with the transverse plane-first rotation sequence may be preferred, especially in cases of hallux valgus deformity.

First ray kinematics in women with rheumatoid arthritis and bunion deformity: a gait simulation imaging study.

OBJECTIVE: The first ray plays a role in the development of bunion foot deformity, but for unknown reasons. This prospective, cross-sectional study investigated first ray kinematics in women with rheumatoid arthritis (RA) and bunion. METHODS: Nine participants having RA-bunion were analyzed in comparison to a control group (n = 10). Data were acquired using a magnetic resonance scanner. Conditions were standardized to simulate gait midstance, heel off, and terminal stance. Foot posture (hallux angle, intermetatarsal angle, arch angle, and calcaneus angle) and relative first ray position angles/helical axis parameters registered across gait conditions were measured. An analysis of variance model compared data between groups and across conditions, and correlation assessed the relationship between selected variables. RESULTS: Eversion of the calcaneus averaged 9°, and adduction of the first ray was increased (F = 6.29, P = 0.02) by ≥4.6° across conditions in the RA-bunion group. There was an interaction (F = 7.73, P = 0.01) for the first ray axis. Followup comparisons identified increased inclination of the first ray axis over middle stance compared to late stance in the group with RA and bunion. There was moderate correlation (r = -0.42) between the calcaneus angle of eversion and inclination of the first ray axis. CONCLUSION: Optimal treatment for bunion has not been defined. This research identified calcaneus eversion and first ray adduction, as well as inclination of the first ray axis as risk factors of bunion. This result may inform the evaluation and treatment of bunion in women with RA.

An image-based gait simulation study of tarsal kinematics in women with hallux valgus.

BACKGROUND: Although not well understood, foot kinematics are changed with hallux valgus. OBJECTIVE: The purpose of this study was to examine tarsal kinematics in women with hallux valgus deformity. DESIGN: A prospective, cross-sectional design was used. METHODS: Twenty women with (n=10) and without (n=10) deformity participated. Data were acquired with the use of a magnetic resonance scanner. Participants were posed standing to simulate gait, with images reconstructed into virtual bone datasets. Measures taken described foot posture (hallux angle, intermetatarsal angle, arch angle). With the use of additional computer processes, the image sequence was then registered across gait conditions to compute relative tarsal position angles, first-ray angles, and helical axis parameters decomposed into X, Y, and Z components. An analysis of variance model compared kinematics between groups and across conditions. Multiple regression analysis assessed the relationship of arch angle, navicular position, and inclination of the first-ray axis. RESULTS: Both the hallux and intermetatarsal angles were larger with deformity; arch angle was not different between groups. The calcaneus was everted by ≥6.6 degrees, and the first ray adducted (F=44.17) by ≥9.3 degrees across conditions with deformity. There was an interaction (F=5.06) for the first-ray axis. Follow-up comparisons detected increased inclination of the first-ray axis over middle stance compared with late stance in the group with deformity. LIMITATIONS: Gait was simulated, kinetics were not measured, and sample size was small. CONCLUSIONS: There were group differences. Eversion of the calcaneus and adduction of the first ray were increased, and the first-ray axis was inclined 24 degrees over middle stance in women with deformity compared with 6 degrees in control participants. Results may identify risk factors of hallux valgus and inform nonoperative treatment (orthoses, exercise) strategies.

Hallux valgus and the first metatarsal arch segment: a theoretical biomechanical perspective.

Hallux valgus is a progressive foot deformity characterized by a lateral deviation of the hallux with corresponding medial deviation of the first metatarsal. Late-stage changes may render the hallux painful and without functional utility, leading to impaired gait. Various environmental, genetic, and anatomical predispositions have been suggested, but the exact cause of hallux valgus is unknown. Evidence indicates that conservative intervention for hallux valgus provides relief from symptoms but does not reverse deformity. Part 1 of this perspective article reviews the literature describing the anatomy, pathomechanics, and etiology of hallux valgus. Part 2 expands on the biomechanical initiators of hallux valgus attributed to the first metatarsal. Theory is advanced that collapse of the arch with vertical orientation (tilt) of the first metatarsal axis initiates deformity. To counteract the progression of hallux valgus, we use theory to discuss a possible mechanism by which foot orthoses can bolster the arch and reorient the first metatarsal axis horizontally.

Consideration of digitization precision when building local coordinate axes for a foot model.

This study investigated whether points digitized for the purpose of embedding coordinate systems into the foot accurately represented the orientation of the bone described. Eight complete data sets were collected from 9 adult cadaver specimens. Palpable landmarks defined 5 segments to include the calcaneus, navicular, medial cuneiform, first metatarsal, and hallux. With use of the Flock of Birds electromagnetic motion tracking device, a single examiner digitized a minimum of 3 points for each segment. Coordinate definitions followed the right-hand rule, with left-sided data converted to right-sided equivalency. Local axes were created where X projected approximately forward, Y upward, and Z laterally. Matrix transformation computations calculated the angular precision in degrees between coordinates built from points digitized pre- and post-dissection of surface tissues covering bone. The condition of post-dissection was considered the criterion standard for comparison. Change about the X-axis represented the angular precision of the coordinate in the frontal anatomical plane; Y-axis in the transverse plane; Z-axis in the sagittal plane. The calcaneus and navicular coordinate axes changed by an average of <3 degrees across conditions. Mean coordinate angulation of the cuneiform X, Y, Z axes changed by 6.0 degrees , 4.6 degrees , 11.9 degrees , respectively. Change in coordinate angulation was largest for the X-axis at the first metatarsal (48.6 degrees ) and hallux (36.5 degrees ). A two-way repeated measures ANOVA found a significant interaction between the axis and segment (F=8.87, P=0.00). Tukey post-hoc comparisons indicated the change in coordinate angulation at the X-axis for the cuneiform, metatarsal, and hallux to be significantly different (P <0.05) from the calcaneus and navicular. The X-axis of the first metatarsal and hallux was different from all other axis-segment combinations except for the Z-axis of the cuneiform. Differences in locating landmarks reduced angular precision of the coordinate axes most in the smallest foot segments where points digitized were located close together. We can recommend the proposed landmarks for the calcaneus and navicular segments, but kinematics determined about the coordinate axes for the small sized medial cuneiform, and the long (X) axis for the first metatarsal and hallux have excessive error.

Arch height and first metatarsal joint axis orientation as related variables in foot structure and function.

BACKGROUND: This study investigated the association of arch height combined with first metatarsal joint axis vertical (V) orientation to the size of the 1-2 intermetatarsal angle (IMA) and first metatarsal adduction/abduction position simulating foot postures during gait, kinematics commonly affected by bunion. MATERIALS AND METHODS: Nine cadaver specimens were mounted in a loading frame. Measures of arch height ratio and IMA were made. With the foot placed in positions seen during normal gait cycle an electromagnetic device measured displacement of the relative angle of rotations between the first metatarsal and navicular, and helical axis (HA) parameters. Canonical correlation analysis assessed the relationship among the variables. RESULTS: A negative relationship (r = -0.73) was found between arch height and first metatarsal HA V-orientation. When considered as combined variables, arch height and metatarsal HA V-orientation accounted for 69% of the variance of IMA and change in first metatarsal adduction/abduction position. CONCLUSION: Orientation of the first metatarsal joint axis was highly variable between specimens but correlated with arch height. The conjoined factors of arch height and first metatarsal HA V-orientation accounted for most of the variance of IMA and change in first metatarsal adduction/abduction position during the sequence of foot position during simulated gait. CLINICAL RELEVANCE: These findings suggest that orthotic arch support could reorient the metatarsal joint axis out-of-vertical and in effect, limit the first metatarsal from displacing into an adducted bunion deformity. These findings could help to explain the pathogenesis of bunions.

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.

A comparison of device measures of dorsal first ray mobility.

BACKGROUND: Devices built by Glasoe and Klaue have been used in several studies to measure first ray mobility. Both devices measure sagittal motion of the first ray in a dorsal direction. The primary difference in the devices is the method of the load imposed. This study investigates whether first ray mobility measured with the Glasoe device is similar to the amount of mobility measured with the Klaue device. METHODS: Using the devices described by Glasoe and Klaue, dorsal first ray mobility was measured in 39 patients who had foot and ankle problems. Paired t-tests were computed to assess for differences between device measures of dorsal mobility. Intraclass correlation coefficient (ICC) and absolute difference values were computed to further assess the agreement in measures. RESULTS: Dorsal mobility measured with the Glasoe device averaged 4.9 mm (1.8 to 9.3 mm). Dorsal mobility measured with the Klaue device averaged 5.2 mm (2.5 to 8.5 mm). Paired t-tests (p = 0.12) revealed no significant difference in measures. An ICC of 0.70 and a mean absolute difference of 0.9 mm (SD 0.8) were found between the two clinical measures further suggesting agreement. CONCLUSION: Results indicated that the two devices possess similar diagnostic accuracy in the measurement of dorsal first ray mobility.

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.

Relationship between static mobility of the first ray and first ray, midfoot, and hindfoot motion during gait.

The relationship between a static measure of dorsal first ray mobility and dynamic motion of the first ray, midfoot, and hindfoot during the stance phase of walking was investigated in healthy, asymptomatic subjects who represented the spectrum of static flexibility. Static first ray mobility of 15 subjects was measured by a load cell device and ranged from stiff (3.1 mm) to lax (8.0 mm). Using three-dimensional motion analysis, mean first ray dorsiflexion/eversion and mid-/hindfoot eversion peak motion, time-to-peak, and eversion excursion were evaluated. Subjects with greater static dorsal mobility of the first ray demonstrated significantly greater time-to-peak hindfoot eversion and eversion excursion (p <.01), and midfoot peak eversion and eversion excursion (p <.01). No significant association was found between static first ray mobility and first ray motion during gait. This research provides evidence that the dynamic response of the foot may modulate the consequences of first ray mobility and that compensory strategies are most effective when static measures of dorsal mobility are most extreme.

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.

Comparison of two methods used to assess first-ray mobility.

Mobility of the first-ray is associated with several common lower extremity disorders. However, the reliability and validity of clinical measurement remains unclear. In this study we examined first-ray mobility by using one hand to stabilize the lesser metatarsals while the clinician's other hand applied a displacement force to the head of the first metatarsal. The amount of mobility was graded as stiff, normal or hypermobile. We then used a well-validated mechanical device to perform similar tests and assessed validity, intrarater reliability and interrater reliability. Three clinicians having varied levels of experience graded first-ray mobility on 15 subjects. A separate investigator measured dorsal mobility with a mechanical device. Both methods of testing were repeated to assess measurement reliability. Reliability was estimated by kappa (K) statistics. Spearman correlation assessed the relationship between mobility graded manually and dorsal mobility measured by device. Manual examination intrarater K values ranged from 0.50 to 0.85, and interrater agreement from 0.09 to 0.16. Manual grading was not related (r = -0.21) to the absolute measure of total dorsal mobility made by device. This brings into question the validity and reliability of manual estimates of first-ray mobility.