Retrograde Reamer Depth Tube Gage for Bone Gap Measurement
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Solution Overview
Problem
Current methods for measuring the depth of tunnels or bores drilled through bone during ligament surgery are inaccurate and difficult to use, leading to suboptimal formation of recipient sockets for tendon grafts.
Innovation Solution
A system comprising a retrograde drill with a tubular shaft, a drill bit, and a cutting member that can rotate between two positions, along with a transparent measurement tube for aligning graduation marks on the tubular shaft, allowing for precise measurement of the bridge bone gap thickness during drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a retrograde drill with a retrograde drill pin and drill depth grommet is used to measure tunnel depth, then depth measurement can be performed, but the measurement is difficult to perform accurately and produces less than accurate measurement results
Solution Approach 1:
The measurement system is segmented into distinct functional components: a retrograde reamer with cutting members for bone removal, a separate measurement tube with transparent wall for visual measurement, and graduation marks on the reamer shaft. This segmentation allows each component to be optimized independently - the cutting members for effective bone cutting and the measurement tube for accurate visual reading of bone thickness.
Solution Approach 2:
The measurement tube acts as an intermediary between the surgeon and the actual measurement. By providing a transparent tube with graduation marks that can be visually aligned with anatomical landmarks (skin surface or bone surface), the system mediates the measurement process to make it more intuitive and accurate compared to direct reading from drill pin markings.
2Ease of manufacture
If the cutting member is disposed at a non-zero angle relative to the longitudinal axis of the tubular shaft, then the retrograde reamer can effectively cut bone, but it becomes difficult to accurately measure the distance between the distal end of the measurement tube and the cutting member
Solution Approach 1:
The measurement approach transitions from attempting to measure along the angled path of the cutting member to measuring in a different dimension - using the longitudinal axis of the tubular shaft as the reference dimension. The graduation marks are positioned on the shaft surface, allowing measurement along the shaft's longitudinal axis rather than along the angled cutting path, thereby simplifying the measurement geometry.
Solution Approach 2:
The measurement tube with its transparent wall and graduation marks creates a visual copy or representation of the measurement scale that can be externally aligned and read. This external measurement reference allows the surgeon to measure bone thickness by aligning the tube with anatomical surfaces, effectively copying the measurement function to a more accessible location rather than attempting to measure directly from the angled cutting member position.
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
A thickness gage including a transparent measurement tube configured to receive and be slidingly engaged over a tubular shaft of a retrograde reamer. The tubular shaft has linear graduation marks on its surface for identifying linear measures for use in measuring a thickness of a bridge bone gap. The linear graduation marks are located on the tubular shaft surface such that at least some of the linear graduation marks can be observed through the transparent measurement tube. Each linear graduation mark, when aligned with a proximal end of the measurement tube, provides a linear measure of the distance between a distal end of the measurement tube and a cutting member of the retrograde reamer positioned so that its central axis is disposed at a non-zero angle relative to a longitudinal axis of the tubular shaft. Such a distance corresponds to the thickness of the bridge bone gap.