Lobe-Lok™ System - The Ultimate Shoulder System

Life span of a prosthetic shoulder will always differ between patients. Many factors are crucial in determining longevity, such as the patient’s overall condition (activity level etc) and the surgical techniques employed. Because a prosthetic joint is not as strong or durable as a natural, healthy joint there is no guarantee that a prosthetic shoulder will last the rest of a patient’s life. All shoulder prostheses may require a replacement at some point.

 

Indications

 

Your physician may determine that a shoulder replacement is appropriate if you have severe pain or significant disability from one or more of the following conditions:

 

• Deterioration of the shoulder joint cartilage (osteoarthritis)
• Inflammation in the lining of the shoulder joint (rheumatoid arthritis)
• Physical injury to the shoulder joint resulting in arthritis (traumatic arthritis)
• Certain breaks in the shoulder bones (fractures)
• A loss of blood supply to the top of the upper arm bone (humeral head) which leads to tiny breaks within the bone and possible collapse (avascular necrosis)

Because the geometry of the prostheses determines the eventual shoulder function of the replacement, the Lobe-Lok™ system has been developed to provide a wide range of anatomic sizes, offsets, displacements and angulation.

Published clinical history

Primary hemiarthroplasty for treatment of proximal articular humerus fractures - Early results with the Lobe-Lok™ Prosthesis (LLP)

Dittel K.-K.1, Rapp M.1, Felenda M.-R.1
1Marienhospital Stuttgart, Clinic of Traumatology, Stuttgart

Introductions: The use of primary hemiarthroplasty in the treatment of complex fractures of the proximal part of the humerus was first popularized by Neer in 1970. With the development of anatomical designed humerus head prostheses the indication has been widened especially under the knowledge of the poor results after conventional reconstruction of four-part-fractures. On the other hand the line of retreat remains impossible. Nevertheless today the primary implantation of a fracture prosthesis can be regarded as the "gold standard" for four-part-fractures with a head splitting situation. Material and Methods: Between 3/2003 and 3/2005 a fracture prosthesis was implanted in 27 patients (23 men, 4 women). The mean age was 77,9 years (range from 54 to 93 y.). 7 patients had a fracture classification 11 C 2-3 and 20 patients a fracture classification 11 C 3-3. In 18 cases between the first and 7th day the fracture prosthesis was implanted because of an acute fracture, in 3 cases as a delayed procedure between the 5th and 8th week after the fracture event. In 6 cases a revisional procedure was necessary after a primary plate osteosynthesis.
With the help of a radiological anatomical point score with regard to the different injury severity and a clinical point score for the intraoperative situation the indication either for a plate osteosynthesis or a primary hemiarthroplasty can be given precisely. The sum of the partial point scores with a total score of over 100 points implicates the indication for an endoprosthesis.

Results: The patient group could be controlled without exception using the constant score. The primary implantations (n = 18) showed the best results with 65 points going down to a level of 55 points in the group with the delayed procedure while those patients who underwent a primary plate osteosynthesis and a second hemiarthroplasty could be calculated with 48 points. The mean postoperative follow-up was 6 months (3 to 24 months). The mean constant score for all patients was 54 points. Postoperative complications following the arthroplasty could be observed in 3 cases. 2 patients presented extended subluxations and 1 patient suffered a periprosthetic fracture requiring a revisional management. 3 clinical cases will round up the presentation of the results.

Conclusions: Primary shoulder hemiarthroplasty as the choice of treatment in four-part proximal articular humerus fractures are associated with satisfactory results. The anatomical design of the Lobe-Lok™ prosthesis allows an excellent refixation of the smaller and greater tuberculum which is the most important measurement for a congruent articulation. Advantages of the implant are the intraoperative variable lengthening of the neck of the prosthesis and a variable head excentricity. The postoperative results will be influenced negatively by postoperative complications requiring a reintervention by secondary retracted tubercula. The fundaments of the technique of implantation refer to a precise anatomical adaptability between prosthesis, bone and soft tissue.