Stemless Shoulder Implant Segmented Insertion
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Solution Overview
Problem
Traditional shoulder arthroplasty procedures require large incisions and significant tissue damage, leading to longer recovery times and increased risk of muscle failure, particularly due to the need to transect and reattach muscles like the subscapularis.
Innovation Solution
A minimally invasive method involving small incisions through the rotator cuff interval, where a prosthetic stemless shoulder implant is inserted without transecting the subscapularis or supraspinatus muscles, using a combination of cutting instruments and a robotic surgical system to resect the native humeral head and implant a base with a hemispherical prosthetic humeral head formed from two coupled portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional shoulder arthroplasty procedure is performed with large incisions and muscle transection, then the prosthetic implant can be securely implanted and provide stable joint replacement, but the tissue damage increases, recovery time lengthens, and muscle failure risk increases
Solution Approach 1:
The prosthetic humeral head is divided into two separate portions that are inserted and coupled independently through the small incision. This segmentation allows the implant components to be delivered through a minimally invasive approach while still achieving stable implantation without requiring large incisions or muscle transection
Solution Approach 2:
The two portions of the prosthetic humeral head are designed to couple together, with one portion inserted first and the second portion nested onto it through the same small incision. This nesting approach allows sequential insertion of implant components through a single small access point, maintaining implant stability while minimizing tissue disruption
2Ease of manufacture
If large incisions are made for implant insertion, then the prosthetic components can be implanted with adequate exposure, but the scarring increases and recovery time lengthens
Solution Approach 1:
By dividing the prosthetic humeral head into two smaller portions, the implant can be delivered through a small incision that provides adequate exposure for insertion while minimizing soft tissue disruption. This segmentation enables feasible implantation through minimally invasive access, reducing scarring and accelerating recovery
Solution Approach 2:
The first portion of the prosthetic humeral head is inserted and positioned before the second portion. This preliminary action allows the initial component to be securely placed through the small incision, creating a stable foundation that facilitates subsequent insertion of the second portion without requiring larger exposure
3Ease of operation
If the subscapularis muscle is transected for implant access, then the surgical approach can be established, but the muscle integrity is compromised and failure risk increases
Solution Approach 1:
Instead of approaching the humeral head through anterior exposure requiring subscapularis transection, the implant portions are inserted through the rotator cuff interval from a superior approach. This dimensional change in surgical access allows adequate implantation while preserving muscle integrity, as the rotator cuff interval provides natural separation between muscle layers without requiring transection
Data Source
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AI summary
A method of implanting a prosthetic stemless shoulder implant may include making an incision into a patient's shoulder area of a patient and passing a cutting instrument through a rotator cuff interval (70) of the patient. A central portion (12) of the native humeral head may be resected and removed so that a central void remains (12'). The same or another cutting instrument may be inserted through the rotator cuff interval and into the central void. Medial and lateral portions (14, 16) of the native humeral head adjacent the central void may be resected and removed. A base (100) of a prosthesis may be implanted into a proximal portion of the humerus after passing the base through the rotator cuff interval, and two humeral head portions (150a, 150b) may be inserted through the rotator cuff interval and coupled to the base and to one another.