Modular • Ease of Insertion • Smooth Stem
“The indications for surgical management of radial head fractures are not well defined in the literature. Fragment size, number, degree of displacement, and bone quality influence decision making regarding optimal management. Associated injuries and a block to motion are also important factors to consider. Good results have been reported after ORIF for selected non-comminuted displaced radial head fractures. Radial head fragment excision and early or delayed radial head excision all have a role in the management of these common injuries. Radial head fractures that are displaced, but are too comminuted to be anatomically reduced and stably fixed with ORIF and which are too large to consider fragment excision (fracture involves greater than ¼ of the radial head), should be managed by radial head excision or arthroplasty. Patients known to have or likely to have an associated ligamentous injury of the elbow or forearm should undergo a radial head arthroplasty because radial head excision is contraindicated.”1
Highly polished articular surface in 12 Head sizes with 10 Stem sizes to address fracture specifics and patient anatomy.
Simple, Morse-taper assembly;120 combinations.
Single Use or Reusable Instruments
Avenger Instrumentation is provided in either a Reusable tray or Sterile Single-use Trays.
INCISION / EXPOSURE
With the patient in a supine position, a midline posterior incision is made just lateral to the tip of the olecranon. A full thickness lateral flap is elevated on the deep fascia. The use of this incision decreases the risk of cutaneous nerve injury and permits access to the medial side of the elbow in case repair of the collateral ligament is needed for stability. Alternatively, a lateral approach to the elbow can be used as depicted.
The radiocapitellar joint is exposed via the fascial interval between the anconeus and extensor capri ulnaris (Kocher approach). Continue to open the joint to expose the radial head. The posterior interosseous nerve (the motor branch of the radial nerve) passes around the radial neck and can be protected by keeping the forearm pronated during the exposure and by limiting the distal dissection. Dissectioninto the supinator muscle should be avoided.
The radial head and fragments are resected and removed. The resection should be perpendicular and at the level of the radial neck fracture. Excessive resection should be avoided. Retract the radial shaft to improve exposure.
REAMER AND STEM SIZING
Create an opening in the medullary canal using the Starter Awl. The smallest Reamer (5.5mm) is then used in the medullary canal. Each Reamer is used sequentially until the largest Reamer that creates an easy fit is used. This “largest fitting diameter” Reamer will correspond to the diameter of the Stem Trial and Implant. The length of the cutting teeth area is equivalent to the standard Stem Implants. A laser mark line on the Reamer shaft corresponds to the long Stem Implants.
After the canal has been reamed and the appropriate size Stem diameter has been selected, it may be necessary to use the Planer to create a smooth contact surface on the radial neck. The Planer features a cut-out to ease insertion.
Using the gathered radial head fragments, use the Head Sizer /Assembly Tray impressions to determine the closest diameter Head Trial and Implant. In cases where 2 diameters may work, select the smaller size.
The selected Trial Stem and Head are assembled and placed into the joint space. The joint is reduced and the sizing is assessed through a full range of motion.
In some cases, it may be necessary to adjust the height of the Head to facilitate proper joint spacing. Plus height sizes (+2mm and +4mm) of the Heads can be used for this purpose.
The Stem Implants are provided in standard and long (8mm longer than standard) lengths to facilitate stability if necessary. A laser mark line on the Reamer shaft corresponds to the long Stem Implants. For this reason, only standard Stem diameter Trials are provided for diameter validation.
Before deciding on the final Implant combination, the size and spacing should be confirmed using fluoroscopy. The lateral and medial sides of the humeroulnar joint space should be symmetric and the coronoid and trochlea should be in contact.
NOTE: It is important to ensure that the joint has not been over-stuffed.
Prior to insertion, the final Implant Head/Stem combination is assembled using the Implant assembly instruments. 1) The Head is placed in the Head Sizer/Assembly Tray and the 2) Stem Morse-taper is inserted into the mating head taper. 3) The Impactor is placed over the stem and firmly struck approximately two to four times with a mallet.
Retract the radial shaft to improve exposure. Using finger control, the Implant is placed into the joint space. If necessary, place the Inserter Cap over the end of the Planer 4) and use this to push the Implant into place. As a final check, manipulate the elbow through its full range of motion. This is done to confirm Implant alignment. Additional confirmation may be done using fluoroscopy. The proximal edge of the Implant should not be more proximal than the most proximal aspect of the radial notch of the ulna (at the PRUJ).
REPAIR SOFT TISSUES AND CLOSURE
The annular and radial collateral ligaments are repaired. The fascial interval between the anconeus and extensor carpi ulnaris muscles is closed. Repair the lateral collateral ligament and extensor muscle origins back to the lateral condyle. Then place the elbow through an arc of flexion-extenion. If elbow instability is present, perform additional ligament repair.
The skin and subcutaneous tissues are repaired in layers.