Optimal glenoid component placement possible with minimal bone deformity
Ianotti J. J Shoulder Elbow Surg. Published online 23 May 2011. doi:10.1016/j.jse.2011.02.011.
Traditional methods to correct moderate to severe glenoid deformity and place the glenoid component within 5° of the ideal position are inconsistent, according to Ohio researchers.
This study, led by Joseph Iannotti, MD, and colleagues at the Orthopaedic and Rheumatologic Institute in Cleveland, Ohio, included 13 patients undergoing primary total shoulder arthroplasty. The researchers sought to test a senior surgeon’s ability to position the glenoid component using standard preoperative planning and surgical bone preparation.
The researchers used a 3-D surgical simulator to assess the patients. To achieve ideal version, the surgeon had to obtain version as close to perpendicular to the plane of the scapula, have the back side of the component make complete contact with glenoid bone and maintain the center peg of the component within bone.
On average, the retroversion angle was 13°. Preoperative glenoid retroversion was greater or equal to 10° in seven cases. The surgeon malpositioned the component with greater than 10° of ideal version in three cases. In cases with less than 10° of preoperative retroversion, the surgeon placed the glenoid component within 10° of ideal version in all cases, the authors wrote.
The researchers found that traditional methods to correct moderate to severe glenoid deformity and place the glenoid component within 5° of ideal position are inconsistent. With minimal bone deformity, they noted that optimal glenoid component placement is possible. “Retroversion greater or equal to 20° makes it difficult to place a pegged glenoid component perpendicular to the plane of the scapula by asymmetric reaming without center peg perforation,” they wrote.
This well-performed study investigated an important topic in total shoulder arthroplasty: the ability of the surgeon to place a glenoid component in the ideal position. This topic is important because glenoid position likely affects the long-term survival of total shoulder arthroplasty.
In six cases with mild preoperative glenoid deformity (<100), an experienced shoulder surgeon using a common technique was able to place the glenoid in an acceptable position each time. However, in seven cases with moderate to severe glenoid retroversion (>100), the glenoid was appropriately placed in only four (57%) instances.
The major weakness of the study, as the authors point out, is that the “ideal” glenoid version for implant survival has not been well-defined. In fact, Walch et al recently reported concerning rates of glenoid subsidence at 5 years postoperative when reaming was performed aiming for neutral version. Nonetheless, Iannotti and colleagues have provided a valuable study that speaks the technical difficulty in glenoid placement, even in the hands of an experienced surgeon.
It is noteworthy that according to a study based on 1998 data, most shoulder replacements are placed by individuals who perform only one to two replacements a year. The technical difficulty and importance of correct glenoid placement lends support to consideration of more sophisticated methods of determining glenoid version intraoperatively (eg, aiming guide or navigation) when substantial preoperative deformity is identified.
Patrick Denard, MD
Department of Orthopaedics and Rehabilitation
Oregon Health & Science University
- Walch G, Young AA, Melis B, et al. Results of a convex-back cemented keeled glenoid component in primary osteoarthritis: Multicenter study with a follow-up greater than 5 years. J Shoulder Elbow Surg, 2011; 20:385-394.
- Hasan SS, Leith JM, Smith KL, Matsen FA. The distribution of shoulder replacement among surgeons and hospitals is significantly different than that of hip or knee replacement. J Shoulder Elbow Surg, 2003;12:164-169.