Adjustable Spacer Instrument for Knee Arthroplasty Ligament Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Knee arthroplasty procedures face challenges in reliably assessing and achieving ligament balance due to the skill-dependent and non-reproducible nature of ligament balancing, which affects the success of the surgery.
Innovation Solution
An adjustable spacer instrument with an angular adjustment mechanism that allows for precise tilting of the femur and tibia relative to each other, enabling surgeons to assess and adjust ligament balance, and a kit including a cutting block for making precise bone cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ligament balancing methods are used, then the surgeon can perform the procedure with existing tools, but the reliability and reproducibility of ligament balance assessment deteriorates due to skill-dependency and variability
Solution Approach 1:
The patent introduces a spacer instrument as an intermediary device between the surgeon and the ligament balancing process. This spacer acts as a mechanical mediator that objectively measures and communicates ligament balance status through tilt indication, removing the skill-dependency from subjective assessment and providing reproducible, quantifiable feedback.
Solution Approach 2:
The patent replaces the traditional mechanical skill-based ligament balancing method with an instrumented system that uses mechanical indicators (tilt of the spacer) to objectively assess balance. This substitution transforms the assessment from a skill-dependent manual process to a measurable, instrument-driven process with improved reliability.
2Manufacturing precision
If precise bone cuts are made to achieve alignment, then the prostheses alignment improves, but the complexity of the surgical procedure increases due to multiple adjustment steps
Solution Approach 1:
The spacer instrument provides self-service functionality by automatically indicating its own tilt status and providing feedback on ligament balance. The instrument serves itself by being placed in the joint space and immediately providing visual or measurable indication of alignment and balance status, eliminating the need for complex external measurement devices or multiple adjustment iterations.
3Adaptability or versatility
If the spacer instrument provides continuous adjustment capability, then the adaptability to different patient anatomies improves, but the device complexity increases due to additional adjustment mechanisms
Solution Approach 1:
The patent implements dynamic adjustability in the spacer instrument, allowing the spacer to be tilted and adjusted during the surgical procedure. This dynamic capability enables the instrument to adapt to different patient anatomies and ligament balance requirements while maintaining a relatively simple construction through the use of basic mechanical adjustment features rather than complex automated systems.
Data Source
AI summary
An adjustable spacer instrument, kit of parts and surgical methods of use in a knee arthroplasty procedure are described. The adjustable spacer comprises a first member having a substantially planar upper surface and a second member having a substantially planar lower surface. An angular adjustment mechanism is interposed between the first member and the second member, and is operable to adjust the degree of tilt between the upper surface and the lower surface. A releasable lock is provided which can maintain the degree of tilt. The spacer instrument can be used with the knee in extension or flexion to allow various cuts or re-cuts to be made to the tibia or femur while the ligaments are in balance or to balance the ligaments.