The Acumed Anatomic Radial Head System provides a comprehensive solution that includes the first anatomically-shaped radial head prosthesis on the market and is equipped with the tools needed to restore the patient's anatomy in a radial head replacement surgery. The system offers standard head and stem combinations, including five left- and five right-specific head options, five stem diameters, and five collar heights. These choices provide the surgeon with multiple implant options and accommodate the individual differences in natural anatomic head and neck shape. In this series of six case studies, Benjamin Goldberg, M. The collar height gauge helps determine the proper implant collar height to restore the natural length of the radius. Broaches, trial heads, and stems are color-coded to assist in identifying components and sizes.
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Standard length stems range from 6—10 mm in diameter in 1 mm increments and 0—8 mm heights in 2-mm increments , and are fully grit-blasted to promote bony ongrowth. The standard stems accommodate a resection window of 9 mm—17 mm. For very distal fractures or revision cases, the long stems range from 6—12 mm in diameter in 2 mm increments , and have 50 mm—65 mm length options in 5 mm increments. These stems accommodate a resection window of 19 mm—28 mm. Several biomechanical studies have discussed the potential long-term value of an anatomically shaped radial head prosthesis.
Heads range from 20—28 mm in diameter in 2-mm increments. The Acumed Anatomic Radial Head System is designed to provide an anatomic implant to replace the patient's native radial head. Designed in conjunction with Shawn W. O'Driscoll, Ph. In addition to the Anatomic Radial Head System, the set may include the Acutrak 2 Mini and Micro instruments and the Locking Radial Head Plate System at the base of the tray to provide multiple solutions all in one set.
These were significantly greater with symmetrical circular prostheses than with asymmetrical elliptical designs. The prosthesis that best mimicked native contact behavior was the anatomical radial head prototype 2 [ARH Solutions] owing to its design for articulating with the capitellum, the lateral trochlear ridge, and the sulcus between. Methods Three commercially available circular radial head designs were compared with an anatomical radial head and 2 modified anatomical prototype radial head designs in 10 cadaveric specimens.
Each prosthesis and specimen combination was loaded in neutral rotation and maximal extension with a custom testing apparatus while measuring contact areas and pressures using thin-film pressure sensors. Results Anatomical radial head prototype 2 had similar radiocapitellar contact areas and mean pressures as the native radial head; all other designs showed significant decreases in contact area and increased mean pressures.
Peak contact pressures were also measured and were significantly elevated with all prostheses tested. Anatomical designs are statistically more likely to mimic normal contact with the lateral trochlear ridge and its adjacent sulcus than circular prostheses. They are also significantly less likely to have contact pressures above the 5 MPa threshold that is thought to be harmful to cartilage. The depth of the articular dish had a significant effect on contact area and pressure.
Conclusion Commercially available radial head prostheses demonstrated reduced radiocapitellar contact areas and elevated contact pressures during compressive loading. The prosthesis that best mimicked native contact behavior was the anatomical radial head prototype 2 owing to its design for articulating with the capitellum, the lateral trochlear ridge, and the sulcus between. The effect of prosthetic radial head geometry on the distribution and magnitude of radiocapitellar joint contact pressures.
J Hand Surg Am. By use of a thin flexible pressure transducer, contact pressures and areas were measured for the native radial head, an anatomic implant, a nonanatomic circular monopolar implant, and a bipolar nonanatomic implant. Results The mean contact areas for the prosthetic radial heads were significantly less than those seen with the intact radial heads at every angle tested P Conclusion The geometry of radial head implants strongly influences their contact characteristics.
In a direct radius-to-capitellum axial loading experiment, an anatomically designed radial head prosthesis had lower and more evenly distributed contact pressures than the nonanatomic implants that were tested.
Influence of radial head prosthesis design on radiocapitellar joint contact mechanics. J Shoulder Elbow Surg. However, it is typically minor, nonprogressive, and of questionable clinical consequence. We hypothesized that stress shielding around radial head prostheses is common but nonprogressive.
In this study, we present a classification scheme to support our radiographic observations. Methods We reviewed charts and radiographs of 86 cases from 79 patients with radial head implants from both primary and revision surgeries between and Exclusion criteria included infection, loosening, or follow-up of less than 12 months.
We saw stress shielding with all stem types: cemented or noncemented; long or short; and straight, curved, or tapered. The average follow-up was 33 months range, mo. Stress shielding was detectable by an average of 11 months range, mo. The 3 cases with circumferential exposure of the stem stage IIb averaged 2.
Stress shielding never extended to the bicipital tuberosity, and there were no cases of impending mechanical failure. Conclusion Stress shielding around radial head prostheses is common, regardless of stem design. Stress shielding around radial head prostheses. ASSH, Published by Elsevier, Inc.
All rights reserved. More than a decade of research and experience has influenced key refinements to the anatomic properties of the prosthesis. Contouring of the medial side of the head has been further defined to track against the radial notch of the ulna. The dish depth increases with head diameter, which is designed to help improve radiocapitellar wear characteristics over the previous generation Anatomic Radial Head. Contouring of the medial side of the head has been further defined to track against the lateral side of the ulna.
With the annular ligament in mind, an S-shaped contour was built into the lateral side of the radial head prosthesis. Hashed Laser Marks: Indicate proper alignment with the lateral aspect of the radius when the forearm is in neutral position. Lister's tubercle may also be used as a landmark for laser mark orientation. Resection Length: Four long stems accommodate resection lengths from 19 mm to 28 mm. The Long Stem Resection Guide is used to measure the length of resection, which corresponds to stem diameter.
Insertion Depth Laser Mark: Corresponds to the stem diameter and proper insertion depth based on equivalent level of resection. Stem Length: Four long stems range from 50 mm to 65 mm in length 5 mm increments and 6 mm to 12 mm in diameter 2 mm increments. Radius Retractor - Designed to help elevate the radius, this tool may assist during reaming, trialing, and insertion of the implant.
Sahu D. Shukla, D. Combinations head and stem combinations. Standard Length Stems Standard length stems range from 6—10 mm in diameter in 1 mm increments and 0—8 mm heights in 2-mm increments , and are fully grit-blasted to promote bony ongrowth. Long Stems For very distal fractures or revision cases, the long stems range from 6—12 mm in diameter in 2 mm increments , and have 50 mm—65 mm length options in 5 mm increments.
Product Overview The Acumed Anatomic Radial Head System is designed to provide an anatomic implant to replace the patient's native radial head. Related Documents. Key Publications. In addition to citing existing scholarly papers, we conduct ongoing clinical research and use this information for validation and continuous improvement to deliver the greatest value to our customers.
Journal Abstract Objective To determine if radiocapitellar contact pressures would be elevated with nonanatomical circular prostheses over those mimicking native anatomy and if such pressures would be related to the depth and contour of the articular dish and to the pattern of prosthetic articulation against the lateral trochlear ridge. Journal Abstract Hypothesis Our aim was to test whether anatomically designed metallic radial head implants could better reproduce native radiocapitellar contact pressure and areas than nonanatomic implants.
Journal Abstract Objective Stress shielding is known to occur around rigidly fixed implants. Key Features. The First and Only Anatomic Radial Head Originally released in , the prosthesis has been used in thousands of radial head procedures over multiple system generations and product line improvements. New Anatomic Design Features Contouring of the medial side of the head has been further defined to track against the radial notch of the ulna. Anatomic Radial Head.
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Elbow Plating System
The Lateral Column Plates improve upon the biomechanics of posterior plating by enabling longer screws in the articular fragments to interdigitate with the screws from the medial side. Designed to offer fixation and compression of fractures of the distal humerus by extending down distally, or wrapping around, the medial epicondyle and extending up the condylar ridge. Specifically designed for isolated capitellar fractures and for surgeons who prefer a 90 degree degree plate application. The Acumed Elbow Plating System offers multiple fixation options for fractures of the distal humerus, olecranon, and coronoid, as well as osteotomies of the olecranon. The Acumed system was the first elbow plating system to offer precontoured, parallel distal humerus plates. Long screws in the Lateral Column Plate are designed to interdigitate with screws from the Medial Column Plate, providing a parallel construct for the stabilization of distal humerus fractures.
Anatomic Radial Head Solutions
Converging and diverging screw angles provide stability and support, and help capture fracture fragments. The Acumed Radial Head Plating System provides an innovative method for the treatment of fractures when the radial head is salvageable. This versatile system of precontoured plates is designed for use in the radial head's "safe zone" and features a straightforward surgical technique that may save time in the surgery room. The system offers a straightforward solution when the radial head is salvageable. Two lengths and two head curvatures provide options for varying patient anatomy and fracture patterns. A radiolucent targeting guide is included in the Radial Head Plating System to assist with threading the locking drill guide into the proximal locking holes.
Radial Head Plating System
Radial Head Plating System Surgical Technique