Revising Failed Reverse Total Shoulder Arthroplasty: Comprehensive Techniques for Precise Explantation of Well-Fixed Implants.

BACKGROUND

With the increased utilization of reverse total shoulder arthroplasty (RTSA), there has been a corresponding increase in the incidence of and demand for revision RTSA. In cases in which the patient has undergone multiple previous surgeries and presents with well-fixed shoulder implants, even the most experienced shoulder surgeon can be overwhelmed and frustrated. Having a simple and reproducible treatment algorithm to plan and execute a successful revision surgery will ease the anxiety of a revision operation and avoid future additional revisions. The extraction techniques described here strive to preserve the humeral and glenoid anatomy, hopefully facilitating the reimplantation steps to follow.

DESCRIPTION

The main principles of implant removal include several consistent, simple steps. In order to revise a well-fixed humeral implant, (1) identify the old implants; (2) create a preoperative plan that systematically evaluates the glenoid and humeral deficiencies; (3) prepare consistent surgical tools, such as an oscillating saw, osteotomes, and/or a tamp; (4) follow the deltoid; (5) dissect the soft tissue with a sponge; (6) dissect the bone with use of an osteotome; and (7) remove the humeral stem in rotation. In cases in which there is also a well-fixed glenoid implant, the surgical procedure will require additional steps, including (8) exposure of the anteroinferior glenoid, (9) disengagement of the glenosphere, and (10) removal of the glenoid baseplate in rotation.

ALTERNATIVES

Alternatives to revision RTSA include nonoperative treatment, implant retention with conversion of modular components, extensile revision surgical techniques, and/or mechanical implant removal. With the advent of modular humeral and glenoid components, surgeons may choose to change the implant components instead of removing the entire humeral and glenoid implants; however, repeat complications may occur if the previous implant or implant position was not completely revised. When confronted with a tough humeral explantation, an extensile surgical approach involves creating a cortical window or humeral osteotomy to expose the humeral implant. This approach can compromise the humeral shaft integrity, leading to alternative and less ideal reconstruction implant choices, the use of cerclage wires, and/or the use of a strut graft, all of which may complicate postoperative mobilization. If glenoid implant removal is necessary, the glenosphere is removed first, followed by the underlying baseplate component(s). If the glenosphere is stuck or if screws are cold-welded, the use of a conventional mechanical extraction technique with a burr or diamond saw may be required; however, this may lead to additional metal debris and intraoperative sparks.

RATIONALE

Revision RTSA can lead to high complication rates, ranging from 12% to 70%, which will often require additional revision surgeries. The first steps to all revision RTSA procedures include careful surgical exposure and component explantation. A simplified approach to expose the humerus and glenoid, coupled with a systematic and atraumatic approach to remove the implants without inadvertent injuries, will prevent surgical complications and the need for re-revision. The proposed comprehensive technique hopefully will allow precise removal of the humeral and glenoid implants while also preserving the remnant humerus or glenoid for future reconstruction.

EXPECTED OUTCOMES

Few studies have evaluated postoperative patient outcomes in revision RTSA. Chalmers et al. performed a meta-analysis and found that patients were able to achieve a mean elevation of 106°, a mean American Shoulder and Elbow Surgeons score of 63, and a mean Single Assessment Numeric Evaluation score of 52. Boileau showed very similar outcomes, with a mean elevation of 107° and a mean adjusted Constant score of 62. These outcomes are slightly inferior to those of primary RTSA, but patients remain satisfied with their improvement from their preoperative function.

IMPORTANT TIPS

Preoperative preparation will reduce intraoperative reparation. Know the existing implant and the unique features of its design, understand the patient anatomy including bone defects, and anticipate all of the potential tools that may be needed.Know your anatomy. The anteromedial deltoid edge will help you identify the scarred-in humeral shaft.Da Vinci said that simplicity is the ultimate sophistication. Some of the most common surgical tools and instruments can be more effective than custom-designed ones.The implant should be removed in rotation.There are some company-specific explantation instruments that can be very helpful. Give the appropriate ones a try, but be prepared to consider alternative solutions.

ACRONYMS AND ABBREVIATIONS

RTSA = reverse total shoulder arthroplastyCT = computed tomographyFE = forward elevation.