Total replacement of trapeziometacarpal joint – type T
1 / 24Páginas

Total replacement of trapeziometacarpal joint – type T Primary Implants

Implant Description Surgical Technique ■ Introduction The design for the T/II and TR type total trapeziometacarpal joint replacement is based on our experience with the T/I type and on the most up-to-date knowledge and experience with similar types of replacements. It permits the simple and perfect fixation of the implant, with minimal bone resection, but also allows for the replacement of the entire trapezium bone, if needed. Optimization of dimensions of the joint replacement's surface ensures maximum scope of mobility, while retaining good functional stability. Finish of the articular...

The components of the total joint replacement can be interchanged - which means that any stem can be used with any neck and cup and PE insert, respectively. The only limitation is the requirement that the diameter of the articulating surface of the PE insert (cup) and the head of the neck is identical - 05 (mm). The total replacement of the trapeziometacarpal joint in an assembly consisting of stem, neck and cup (I and II) is intended for primo-implantation in the case of damage to the articulating surface of the trapezium and metacarpal bones that cannot be treated conservatively. In...

Implant Description Surgical Technique TMCJ − TEP Cementless Stem (Type T and T/II) The metacarpal component is designed symmetrically, e.g. identical for both the right and left hand, and is supplied in 5 sizes. It is manufactured from Ti6Al4V alloy according to ISO 5832-3. The external surface of the upper part is coated with plasma sprayed Ti (type T) or double layer Ti + HA (type T/II). The lower end of the stem of about 1/3 the length is finely sprayed. The stems are intended for assembly with any type of neck. Fig. 2 - TMCJ - Stem - range of 5 dimensions TMCJ − TEP Neck (Type T/II)...

TRAPEZIUM REPLACEMENT – Type TR The assembly of the trapezium replacement is comprised of two individual components (trapezium replacement and PE insert), and is intended for total trapezium replacement in the assembly of a total replacement of the trapeziometacarpal joint. The replacement body is barrel-shaped, with an elliptical cross-section, and is designed in three sizes, with the largest diameter of 14/15, 15/16 and 16/17 (mm), and a height 10 (mm). The external surface has a rim on one side intended for stabilization using the radial part of radial carpal flexor, and two transversal...

Implant Description Surgical Technique of trapezium, at surgeon’s discretion. The following steps of operation’s individual phases remain unchanged. Approach Instruments make it possible to implant the joint replacement comfortably using any of standard surgical approaches used for implanting TMC joints without requiring any substantial change in surgical procedures normally used at given workplace. Standard approach is dorsal approach, for it makes use of all of advantageous features of the instruments. (Fig. 1 ). Process is not influenced by use of a tourni-quet to stop blood flow. With...

1. Resecting the base of the first metacarpal (M1) The following steps prepare medullary canal for the TEP stem. Firstly, open the bone marrow canal (see Fig. 3 ) a reamer drill of 2÷3 mm in diameter may be used). Thereupon we assemble resection block’s holder and the resection block properly and induce the assembled set into the open canal (see Fig. 4a ). After determining the resection level, we secure set using one or two fixation wires (Ø1.2 mm) that we induce through the holes in resection block (see Fig. 4b and 4c ). Thereupon we remove resection block’s holder and, using oscillation...

Implant Description Surgical Technique 2. Preparing medullary canal for TEP stem During pre-operation planning we could merely estimate probable size, but it is only after preparing bone marrow cavity that we are able to determine size correctly. Using the rasps, from the smallest to the largest, we work on medullary canal gradually until intimate contact of the rasp’s larger surface with the cortical bone is reached (see Fig. 6a ). Simultaneously, we keep checking the depth of rasp’s penetration – the upper end of rasp indicates depth of the implant’s position (see Fig. 6b ). After...

3. Preparing the trapezium Firstly, using an oscillation saw, we resect the trapezium. Purpose of the resection is to remove all residue cartilage and sclerotic bone, as they do not ensure good support for the cup. Resection should be as small as possible, bearing in mind however, that the bone must cover the entire external surface of the cup induced subsequently. Level of resection on trapezium should be parallel with base M1 of the first MCP joint (see Fig. 9a ). Preferably, it is possible to use an oscillating saw (see Fig. 9b ). Fig. 9a - Articulated trapezium surface Before we modify...

Implant Description Surgical Technique Exact positioning of matrix (i.e., in the center of resected facet) is very important for correct positioning the cup and its proper fixation in the trapezium. The location for inserting the guidewire can also be determined or verified using a test spike from the instruments for the inserted test stem. The position of the tip of the spike inclined towards the trapezium bone corresponds to the center of the head of the neck in the implant assembly. In this phase of surgery, we recommend trimming the upper surface of the trapezium using a trimming cutter...

The medullary canal's shape and dimensions are checked with aid of 9 and 10 mm matrixes (see Fig. 14a and 14b ). Only when we plan to use cementless cup keep the wire implement in cup after compilation of medullary canal. The matrixes may be used for preliminary functionality testing during the first trial fitting in the trial assembly using a trial stem, trial neck, and trial “cup” (matrix). However, no guide wire may be induced in the trapezium during this trial. 6. Trial Fitting of Joint After finishing the medullary canal in metacarpus and trapezium, we are ready to check position of...