These authors compared the ability of stemmed (21 patients) and stemless (58 patients) implants to radiographically restore native glenohumeral anatomy. Preoperative and postoperative radiographs were assessed for humeral head height, humeral head centering, humeral head medial offset, humeral head diameter, humeral neck angle, and lateral humeral offset.
The radiographic measurements demonstrated no differences between stemmed and stemless shoulder implants.
Comment: This study compared AP radiographs before and after arthroplasty and characterized the degree of restoration in terms of the match between the pathologic and the reconstructed appearances in a single (frontal) plane. The authors suggest that "reproduction of native shoulder anatomy leads to superior outcomes", although the relationship between the degree of anatomical restoration and the patient reported outcomes was not examined in their study.
One of our goals in humeral arthroplasty is the alignment of the upper aspect of the prosthesis with the "berm" (the cut edge of the humeral neck, see arrow in figure below left), so that the cuff insertion approaches the tuberosity properly (below center) without an increase in tendon tension that could lead to subsequent cuff failure (below right).
Much of the pathology of glenohumeral arthritis is not seen on an AP radiograph, but rather is revealed by an axillary view obtained with the arm elevated into a position of function as shown in the two examples below. The findings of posterior instability would not have been suspected from the AP radiographs.
In such shoulders the goal of shoulder arthroplasty is not so much the restoration of preoperative anatomy, but rather restoration of functional mobility and stability. Such reconstructions often require solutions that, in fact, do not restore "normal" anatomy, but may use, for example, non-anatomic anteriorly eccentric humeral head components as shown below.
It would be of interest to see data comparing the preoperative and postoperative axillary views in this series of cases to better understand the three dimensional aspects of the reconstructions. It is not clear whether a stemless humeral component enables the use of an eccentric humeral head if it should be necessary to address posterior instability.
Comment: This study compared AP radiographs before and after arthroplasty and characterized the degree of restoration in terms of the match between the pathologic and the reconstructed appearances in a single (frontal) plane. The authors suggest that "reproduction of native shoulder anatomy leads to superior outcomes", although the relationship between the degree of anatomical restoration and the patient reported outcomes was not examined in their study.
One of our goals in humeral arthroplasty is the alignment of the upper aspect of the prosthesis with the "berm" (the cut edge of the humeral neck, see arrow in figure below left), so that the cuff insertion approaches the tuberosity properly (below center) without an increase in tendon tension that could lead to subsequent cuff failure (below right).
Much of the pathology of glenohumeral arthritis is not seen on an AP radiograph, but rather is revealed by an axillary view obtained with the arm elevated into a position of function as shown in the two examples below. The findings of posterior instability would not have been suspected from the AP radiographs.
It would be of interest to see data comparing the preoperative and postoperative axillary views in this series of cases to better understand the three dimensional aspects of the reconstructions. It is not clear whether a stemless humeral component enables the use of an eccentric humeral head if it should be necessary to address posterior instability.
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