Orthopaedics
Wrist and Elbow Prosthesis
uHead™
The Avanta uHead™ prosthesis is anatomically designed to replicate the distal ulnar head and its contact within the sigmoid fossa of the distal radius. The prosthesis is available in multiple sizes that accommodate the anthropomorphic variations of the distal radio-ulnar joint (DRUJ). During prono-supinatory activities, the head component provides a smooth articulation with cartilage at the sigmoid notch and undersurface of the triangular fibro- cartilage (TFC). In addition, the head component has holes that accommodate anchoring of soft tissues, specifically the TFC, extensor carpi ulnaris (ECU) subsheath, and the ulnocarpal ligament complex, to provide stability while soft tissue maturation occurs. The stem component is tapered for rigid intramedullary fixtation and can be used with or without bone cement. The head and stem components are coupled together using a Morse taper and are modular to accommodate variations in anatomy. The stems are also offered in an extended collar configuration for revision of failed Darrach and Suave-Kapandji procedures.
RE-MOTION™ Total Wrist
The RE-MOTION™ Total Wrist System is an anatomically designed implant that requires no resection of the distal radius. The RE-MOTION Total Wrist System is available with Precise Guidance Technology™ (PGT) Instrumentation. PGT is a proprietary instrument system to facilitate the correct anatomical placement of the RE-MOTION™ Total Wrist Implant (Total Wrist).
The RE-MOTION™ Total Wrist implant is provided in left and right hand configurations with geometrically scaled sizes to accommodate anthropomorphic size variations of the radio-carpal joint. The prosthesis is composed of three primary articulating components: radial, carpal ball, and carpal plate.
The radial component is designed much like a surface replacement arthroplasty (SRA) in that it seats against the scaphoid and lunate fossa and preserves the peripheral rim of the distal radius with its important ligamentous and soft tissue attachments. This design configuration requires minimal resection of the distal radius and preserves the sigmoid notch and articulation with the head of the distal ulna.
The carpal plate component is a low profile design that minimizes the amount of bone resection and does not interfere with the normal function of the wrist extensor tendons. The carpal plate has a central stem for insertion into the capitate and accommodates two carpal screws for fixation to the trapezoid and hamate within the distal carpal row.
The carpal ball component acts as an intercalated segment that articulates with both the radial and carpal plate components. The primary articulation occurs with the radial component. This articulation is ellipsoidal and acts along two perpendicular axes of rotation, which lie in coronal and sagittal planes whereby permitting motions of flexion-extension and radio-ulnar deviation respectively. The convexity of the radial component’s articular geometry resists ulno-volar directed forces that can cause excessive wear and implant subluxation. The secondary articulation of the carpal ball occurs with the carpal plate component. This articulation is rotational about an axis aligned with the longitudinal axis of the third metacarpal. This additional degree of freedom diverts rational forces from the bone implant interface that can cause loosening leading to implant failure. The additional laxity also provides compensation for potential misalignment of the device due to advance deformity caused by rheumatoid or degenerative arthritis.
Precise Guidance Technology allows surgeons to perform total wrist arthroplasty with consistent and predictable outcomes. In one tray, the PGT instrumentation provides a complete solution for total wrist arthroplasty. The set combines left- and right-hand components and all items necessary to perform the procedure.
