Abstract
Revision of the humeral component in shoulder arthroplasty is frequently necessary during revision surgery. Newer devices have been developed that allow for easy extraction or conversion at the time of revision preserving bone stock and simplifying the procedure. However, early generation anatomic and reverse humeral stems were frequently cemented into place. Monoblock or fixed collar stems make accessing the canal from above challenging. The cortex of the Humerus is far thinner than the femur and stress shielding has commonly led to osteopenia. Many stem designs have fins that project into the tuberosities putting them at risk for fracture on extraction.
Extraction starts with an extended deltopectoral incision from the clavicle to the deltoid insertion. The proximal humerus needs to be freed from adhesions of the deltoid and conjoined tendon. The deltopectoral interval is fully developed. Complete subscapularis and anterior capsular release to the level of the latissimus tendon permits full exposure of the humeral head. After head removal the stem can be assessed for loosening and signs of periprosthetic joint infection. The proximal bone around the fin of the implant should be removed from the canal. If possible, the manufacturer's extractor should be utilised. If not, then a blunt impactor can be placed from below against the collar of the stem to assist in extraction. With luck the stem can be extracted from the cement mantle. If there is no concern for infection, the cement-in-cement technique can be used for revision. Otherwise, attempts should be made to extract all the cement and cement restrictor, if present. The small cement removal tools from the hip set can be used and specialised shoulder tools are available. An ultrasound cement removal device can be very helpful. The surgeon must be particularly careful to avoid perforation of the humeral cortex. This is especially important when near the radial nerve as injury can occur
When a well-fixed stem is encountered, an osteotomy of the proximal humerus is necessary. The surgeon can utilise a linear cut with an oscillating saw along the bicipital groove for the length of the implant. An osteotome is used to crack the cement mantle allowing stem extraction. Alternatively, a window can be created to offer additional access to the cement mantle.
In the event the surgeon has required an osteotomy or window, cerclage wires, cables or suture will be needed and when the bone is potentially compromised, allograft bone graft struts (tibial shaft) are used for additional support. Care is needed when passing cerclage wires to avoid injury to the radial nerve which is adjacent to the deltoid insertion.
If infection is suspected or confirmed an ALBC spacer is placed. When single stage revision is planned both cemented and uncemented stem options are available. Cement placed around the humeral stem has been suggested to decrease infection incidence.
Revision of cemented humeral stems is a continued challenge in revision shoulder surgery. Newer systems and reverse total shoulder options have improved the surgeon's ability to achieve good outcomes when revising prior shoulder arthroplasty.
