Stemless Shoulder Replacement: A New Concept for Shoulder Arthritis

David W. Cruickshank, MD, BSc, FRCS(C); Ryan T. Bicknell, MD, MSc, FRCS(C)

Disclosures

Curr Orthop Pract. 2017;28(2):153-159. 

In This Article

Abstract and Introduction

Abstract

Stemless shoulder arthroplasty implants allow a surgeon to more accurately recreate a patient's normal anatomy because the implant is contained solely within the proximal humeral metaphysis. As well, this has the potential to avoid humeral stem-related complications, such as intraoperative fracture, periprosthetic fracture, and difficulties with revisions and stem extraction. Canal sparing shoulder arthroplasty implants have been used since 2004, and currently six manufacturers have designs available. Short-term to mid-term results are promising, with low rates of loosening and revision, similar to stemmed implants. However, long-term outcomes are not yet available. Stemless reverse shoulder arthroplasty offers the same potential benefits as anatomic stemless designs. Some implants are a convertible design that allows conversion from an anatomic to a reverse humeral component while leaving the metaphyseal implant in place. Short-term to mid-term outcomes are available only for one implant and are promising. Long-term outcomes of stemless reverse shoulder implants are not known.

Introduction

The first shoulder arthroplasty dates back to 1893, performed by a French surgeon, Jules Emile Péan.[1] This involved using a platinum and rubber prosthesis to replace a shoulder that was debrided for tuberculosis. Anatomic humeral head replacement began to gain interest in the 1950's, when Krueger reported the first anatomic humeral head replacement for avascular necrosis.[2] However, it was not until 1974 that Neer reported outcomes on the first total shoulder arthroplasty, consisting of a prosthetic glenoid component and the Vitallium humeral head.[3]

Stemmed implants have offered a good solution for humeral head replacement, but complications relating to the insertion as well as revision have lead to the creation of canal-sparing designs. Although fairly rare, previous reports of stemmed implants have estimated the rate of intraoperative humeral fracture to be 1.5%,[4] and the rate of periprosthetic humeral fracture after anatomic shoulder arthroplasty to be 1.6%[5] to 2.4.[6] Other stem-related complications include proximal stress shielding, as well as revision difficulties including stem extraction, cement mantle resection, bone loss and periprosthetic fracture.[7]

Proximal humeral anatomy has great variation with respect to the relationship of the shaft to the humeral head.[8–10] Version, inclination, and offset differences between patients have made it difficult for monoblock stem prostheses to recreate normal anatomy. Newer modular implants provide options to adapt the implant to the patient's anatomy, but there are still limitations, especially in cases of malunion, humeral canal deformities, or post-fracture sclerosis.

Stemless implants avoid many of these anatomical concerns by creating an implant that is contained totally within the metaphysis, and its position is determined by an anatomic neck cut, automatically adjusting for the patients natural version, inclination and offset. The first canal-sparing device, the Biomet Total Evolutive Shoulder System (TESS, Biomet, Warsaw, IN, USA), was available for implantation in Europe in 2004. The TESS was different from previous shoulder-stemmed arthroplasty systems in that the humeral component consisted of a highly porous coated 6-arm corolla to which the anatomic humeral head component is attached (Figure 1). Currently, there are six companies that have stemless humeral components on the market worldwide. Of these, only the Simpliciti (Wright Medical, Memphis TN; formerly Tornier), has recently been approved by the Federal Drug Administration (FDA) for use in the United States.

Figure 1.

Biomet Total Evolutive Shoulder System.

Before the advent of stemless humeral implants, humeral resurfacing implants have been available. It is important to note that there are large differences between the designs of stemless and resurfacing humeral implants. Resurfacing implants use conical reamers to shape the humeral head to accept a metal resurfacing cap that maximizes bone preservation, while stemless designs utilize an anatomic neck cut. The disadvantage to resurfacing is difficulty with glenoid exposure, and therefore ability to implant a glenoid component, as well as difficulty with estimating the correct humeral head size and position when reaming away the head instead of performing an anatomic neck osteotomy. These difficulties are overcome with stemless designs that allow similar glenoid exposure as with stemmed implants and allow the surgeon to recreate the humeral head size and position as with stemmed implants. Therefore, stemless implants allow the surgeon to perform the same operation as a stemmed implant but without the potential drawbacks related to stemmed humeral implant designs.

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