Impaction autografting of the medial calcar in anatomic shoulder arthroplasty

Impaction humeral autografting using bone from the resected humeral head can provide an alternative option to cemeting the humeral component in anatomic shoulder arthroplasty in cases of osteopenia. This method is routinely performed at the University of Washington for standard size smooth stems and indeed is a good method of fixation of the stem. In case the stem has to be removed in the future resection is easy and not problematic due to avoidance of the excessive adherence or ingrowth of the stem to the humerus. In contrast to the hip arthroplasty, the shoulder arthroplasty stems do not see the torsional forces seen within the femoral canal and for that reason impaction autografting in primary anatomic shoulder arthroplasty is a valuable and appropriate method of fixation of the stem. The use of this technique in cases of implantation of a short stem is even more critical when the proximal humerus endosteal bone is osteopenic. The case below illustrates the radiographic appearance of this method. In this case the "fine tuning of the position of the humeral stem" was performed with impaction grafting as well as the press fit.

The arrow points in the humeral head autograft placed in the endosteal canal with impaction in this case. Radiopaque appearance indicates the increased density of the bone at the medial calcar reinforcing the fixation. Theses x-rays were obtained immediately post-op. We prefer to fix the component by impaction grafting the inside of the humerus (using bone harvested from the humeral head that has been removed) until a tight press fit of the implant is achieved.

The method and picture taken from UW Shoulder and Elbow Service is seen below as well as the their recent publication indicates 93.4% survivorship of the stem at 5 years with minimum of 2 year follow up:

Impaction autografting: bone-preserving, secure fixation of a standard humeral component

Robert M. Lucas, MD

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Jason E. Hsu, MD

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Albert O. Gee, MD

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Moni B. Neradilek, MS

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Frederick A. Matsen III, MDCorrespondence information about the author MD Frederick A. MatsenEmail the author MD Frederick A. Matsen

• J Shoulder and Elbow Surgery 

November 2016Volume 25, Issue 11, Pages 1787–1794

Background

When fixed with bone ingrowth, a tight diaphyseal press fit, or cement, the humeral component of a shoulder arthroplasty may present problems of malposition, stress shielding, or periprosthetic fracture or difficulty with removal at revision arthroplasty. We have avoided the need for these fixation methods by using impaction cancellous autografting of the humeral stem, minimizing contact between the prosthetic stem and the humeral cortex. This study presents the radiographic survivorship of impaction-autografted humeral implants using component subsidence as the primary endpoint.

Methods

We reviewed 286 primary anatomic shoulder arthroplasties having an average follow-up of 4.9 ± 2.7 years. Initial postoperative radiographs and minimum 2-year follow-up radiographs were evaluated by 3 observers to assess subsidence.

Results

Two different implants (Humeral Replacement Prosthesis [HRP] and Global Advantage prosthesis) were used. Of 286 stems, 267 (93.4%) had not subsided. The Global Advantage prosthesis had a subsidence-free survival rate of 98.5% at 5 years. The stiffer-stemmed HRP used early during the study had a higher rate of subsidence compared with the currently used Global Advantage stem (hazard ratio, 5.6; P = .001). Radiolucent lines of 2 mm or greater were less common for the Global Advantage prosthesis than for the HRP in each of 7 zones (P < .001). Total shoulder arthroplasty was associated with a higher rate of subsidence compared with hemiarthroplasty (hazard ratio, 2.6; P = .12).

Conclusions

Impaction autografting provides a secure, durable, bone-preserving means of humeral component fixation in anatomic shoulder arthroplasty.