From the Guidelines
To identify a hypermobile first ray on the foot, perform a clinical examination with the patient seated and the foot non-weight bearing, as imaging studies like radiography, CT, and MRI are not typically used as the first line of evaluation for this condition 1. When evaluating a patient for a hypermobile first ray, it is essential to consider the clinical presentation and perform a thorough physical examination. The examination should include stabilizing the lesser metatarsals with one hand while using the other hand to grasp the first metatarsal head and move it in dorsal and plantar directions.
- A hypermobile first ray will demonstrate excessive movement compared to normal, particularly in the dorsal direction.
- Quantitatively, dorsal excursion greater than 8-10mm or significantly more movement than the adjacent metatarsals indicates hypermobility.
- Weight-bearing tests are also valuable; observe for flattening of the medial longitudinal arch and pronation during standing.
- The "paper pull-out test" can be performed by placing paper under the first metatarsal head while the patient stands, then assessing resistance when pulling the paper out.
- Easy removal suggests hypermobility. Hypermobility is often associated with conditions like hallux valgus, metatarsalgia, and plantar callus formation under the second metatarsal head due to load transfer from the unstable first ray.
- This assessment is crucial because hypermobility can contribute to various foot pathologies and may require specific treatment approaches, including orthotic therapy or, in severe cases, surgical stabilization. While imaging studies like radiography, CT, and MRI can be useful in evaluating other causes of foot pain, they are not typically used as the first line of evaluation for hypermobile first ray, as they may not provide sufficient information to diagnose this condition 1.
From the Research
Identifying Hypermobile First Ray on Foot
To identify a hypermobile first ray on foot, several methods can be employed, including:
- Clinical evaluation: determining sagittal motion (the grasping test) and transverse motion (the clinical squeeze test) 2
- Radiographic evaluation: measurements from the modified Coleman block test (for sagittal motion) and the radiographic squeeze test (for transverse motion) 2
- Assessment of signs such as the presence of a dorsal bunion, intractable plantar keratosis beneath the second metatarsal head, and arthritis of the first and second metatarsocuneiform joint 2
- Operational definition: dorsal displacement that measures greater than 8 mm, accompanied with signs and symptoms consistent with loading insufficiency of the first ray 3
Key Characteristics of Hypermobile First Ray
Some key characteristics of a hypermobile first ray include:
- Excessive motion at the first metatarsocuneiform joint, with greater than 4 degrees of sagittal motion and greater than 8 degrees of transverse motion 2
- Increased joint forces, with higher resultant metatarsocuneiform and metatarsophalangeal joint forces compared to a normal foot 4
- Abrupt change of metatarsocuneiform joint force in the medial-lateral direction 4
- Presence of cortical hypertrophy along the medial border of the second metatarsal shaft, a cuneiform split, the presence of os intermetatarseum, and the round shape and increased medial slope of the first metatarsocuneiform joint 2
Debate on Terminology
There is an ongoing debate on the terminology used to describe hypermobile first ray, with some researchers suggesting that the term "hypermobility" is inconsistent with the physics applied to the foot, and instead proposing the use of terms such as "stiffness" and "compliance" 5