Mechanical measuring device for simple, reproducible and accurate measurement of leg length difference
A stable measuring table with guide rails and sensors addresses the imprecision and unreliability of existing leg length measurement methods, providing accurate and cost-effective, radiation-free leg length discrepancy assessments.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2026-01-16
- Publication Date
- 2026-04-09
AI Technical Summary
Current methods for measuring leg length discrepancies are imprecise, non-reproducible, and require expensive hospital visits with radiation exposure, making it difficult to accurately determine differences between legs.
A dimensionally stable measuring table with guide rails and sliding footrests, equipped with a measuring sensor, ensures accurate and reproducible leg length difference measurements without additional equipment or radiation, allowing for precise determination of leg length discrepancies.
Enables precise and reproducible leg length difference measurements in a clinical setting, reducing costs and eliminating radiation exposure, and is applicable for pre- and postoperative monitoring and orthopedic aid determination.
Smart Images
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Abstract
Description
[0001] Current methods for measuring leg length discrepancies resulting from malformations or surgery are particularly problematic due to the difficulty of defining a clear and reducible measurement range (starting and ending points) for each leg. Furthermore, the procedures used in orthopedic practices are imprecise and not reproducible. Accurate measurements can currently only be performed in hospitals, which involves considerable expense, time, and additional radiation exposure for the patient.
[0002] Therefore, in orthopedic practice, any potential difference is often determined visually only by inspection and, if necessary, with the aid of spacers. This method is not only very inaccurate but also not reproducible.
[0003] The applicant for the described measuring device was diagnosed with a 5-10 mm length discrepancy in his left (operated) leg following hip surgery, which would have necessitated a shoe insert in his right shoe. A measurement using a prototype of the described device determined that the left (operated) leg was exactly 10 mm too short, requiring an insert in the left shoe. This measurement was subsequently verified by an orthopedist using an X-ray.
[0004] For the orthopedic diagnoses described, it is not necessary to measure the individual leg lengths, but only to determine any potential difference between them. Therefore, it is not necessary to define a fixed point on the body for the measurement; it is only essential to ensure that any difference can be accurately determined and reproduced.
[0005] For this purpose, a dimensionally stable measuring table (glued wood, plastic, metal) is required, which should be at least 110 cm long and approximately 60 cm wide. Guide rails are recessed into the sides of the measuring table at intervals of approximately 20 cm from the center, and a measuring scale is mounted parallel to these rails (see Nos. 2 and 3 of Drawing 1). A sliding footrest (roller bearing or similar – see No. 5 of Drawing 1) is located in each guide rail, and a measuring sensor (see No. 4 of Drawing 1) is attached to the side of this footrest. To avoid measurement inaccuracies, the footrest should be 40 cm long to ensure that the user's foot rests completely against it.
[0006] Furthermore, it must be ensured that the patient lies on the measuring table parallel to its side edges. To guarantee this, the measuring device should, as already described, be at least 110 cm long and approximately 60 cm wide, and have a colored marking in the middle between the top and bottom (see number 1 in diagram 1). This facilitates precise alignment of the patient on the measuring table.
[0007] The position of each footrest can now be read on the measuring scale with millimeter precision. The delta of the measurements thus accurately describes any difference in leg length and is reproducible at any time, since – regardless of whether the measuring device is placed slightly higher or lower on the patient – the measured delta always shows exactly the same result.
[0008] The measurement procedure is shown schematically in drawing 2.
[0009] To prevent the measuring table from taking up too much space in practice when not in use, it can be designed to be foldable in the longitudinal direction as well, without affecting the measurement result.
[0010] The same applies to the footrests. Besides the space requirement, the patient has to lie down on the measuring table, and protruding footrests could make this somewhat difficult. Therefore, for each application, the footrests can either be inserted into the guide rails from below or – in which case, foldable – remain in the measuring table.
[0011] The measuring device is universally applicable (clinic / practice) for precise pre- or postoperative measurement / monitoring before / after orthopedic procedures such as hip, leg, or knee surgeries, for measurements related to orthopedic aids (e.g., determining the thickness of shoe inserts), and for determining the length of orthoses, without additional costs or equipment. Furthermore, it avoids additional radiation exposure for patients.