Technique pearls for revision shoulder arthroplasty aid in preventing fracture, preserving bone stock
Shoulder arthroplasty has become more prevalent in recent years, with growth rates being recently comparable to or higher than hip and knee arthroplasty. Reportedly, the treatment of shoulder osteoarthritis, proximal humerus fracture and rotator cuff tear arthropathy via shoulder arthroplasty has yielded consistent good to excellent results. As indications expand and more shoulder replacements are performed, there has been an increased number of failures and need for revision procedures.
The differential diagnosis for pain and limitation of function after a shoulder replacement is broad. Glenoid component loosening remains the most common reason for failed reconstructions. Other modes of failure include glenoid erosion, instability from component malpositioning, infection, periprosthetic fracture, and rarely, humeral loosening.
Revision shoulder arthroplasty presents a difficult scenario due to the risk of fracture and loss of bone stock. Because the humeral component is rarely loose, extracting a well-fixed prosthesis presents a challenge. With the use of bony ingrowth humeral stems and improved technique in making stable cement mantles for the glenoid and humeral components, the incidence of fracture during extraction is significant. According to Wall and colleagues, there is a 24.1% risk of iatrogenic fracture in revision procedures. Excessive bone loss can cause humeral shortening, loss of deltoid tension and inability to reattach the rotator cuff — all leading to early failure.
A safe window and L-shaped osteotomy have been described for humeral stem extraction and cortical osteotomies. These osteotomies were originally developed for extraction of the femoral stem in hip arthroplasty. Unlike the femur, the cortex of the humerus is thinner, making such cortical osteotomies difficult. These traditional osteotomies can risk loss of tuberosities, leading to shoulder dysfunction. Fracture of the humerus during component extraction has also been associated with radial nerve injury.
A technique using a saw to divide the polyethylene backed glenoid into sections for piecemeal removal has been described for glenoid components that are well-fixed. This carries the risk of denuding glenoid bone stock. For metal-backed or hybrid glenoids, manufacturer tools and carbide tip burrs and saws are oftentimes required for extraction, resulting in large deficits in glenoid bone stock after extraction.
We present simple techniques for revision shoulder arthroplasty using a telescoping osteotome technique for glenoid removal, an open-book (vertical) osteotomy technique for extraction of the humeral stem and the use of an ultrasonic device and carbide burr for clearing bone and cement mantles.
Indications for surgery
Indications for revision shoulder arthroplasty include intractable pain and limitation of function from failed shoulder arthroplasty, whether it be from component loosening, component malposition, periprosthetic fracture or instability. In our practice, all patients undergo preoperative laboratory tests for infection — white blood cell, erythrocyte sedimentation rate, C-reactive protein, interleukin (IL)-1, IL-6, tumor necrosis factor alpha — and are sent for metal and cement testing for allergies.
Preoperative radiographs and CT scans are obtained for prosthesis comparison with the University of Washington Shoulder Site and evaluated for the presence of cement. Prosthetic identification is an important step in surgical planning, such as in the case of bony ingrowth stems. It is crucial to assess for fluted stems and measure the length of the grit-blasted portion of the stem. If fluting is present or the entire surface of the stem is grit-blasted, we proceed immediately to humeral osteotomy instead of attempting a removal of the humeral component with a slap hammer to decrease the risk of fracture. Contraindications to this procedure include patients who are medically unstable for surgery.
The patient is placed in a supine position on the operating table with the scapula of the operative extremity elevated under a rolled towel and the operative shoulder over the edge of the table to improve visualization during fluoroscopic imaging. In our practice, a deltopectoral approach and subscapularis tenotomy peel is used to gain access to the glenohumeral joint.
To address the humerus, the shoulder is dislocated. To remove the prosthetic head, the manufacturer’s extraction device or osteotome can be used. For well-fixed stems, we proceed next to humeral osteotomy to decrease fracture risk. For loose uncemented or cemented stems, a 2-mm drill is used to make perforations along the cement/bone or prosthesis/bone interface to aid in extraction (Figure 1). A carbide tip high-speed burr with a matchstick attachment can be used to aid in debonding the cement/bone or bone/prosthesis interface.
Once the cement mantle has been debonded proximally or prosthesis/bone interface has been disrupted, a vertical osteotomy is performed. Cautery dissection is used to expose the humerus vertically, beginning just lateral to the bicipital groove and extending distally between the deltoid and pectoralis insertions. Blunt dissection posteriorly around the humerus is performed to identify and protect the radial nerve. An oscillating saw is then used to create a vertical linear unicortical osteotomy. Literature on hip arthroplasty has demonstrated that an osteotomy via sagittal saw perpendicular to the surface of the femoral cortex increases fracture risk, so a carbide tip high-speed burr is used as the osteotomy is carried distally to prevent fracture risk. Fluoroscopy is used to ensure that the osteotomy is carried to the distal end of the prosthesis.
A series of osteotomes are then gently inserted into the humerus and rotated perpendicularly to the osteotomy to gently open the humeral shaft like a book. Once a gap is created, the humeral component can be extracted via gentle mallet extraction (Figure 2).
After extraction of the humeral head, an ultrasonic device is used to remove any cement mantle. This device works by converting manual vibrations into thermal energy, liquefying and fracturing the cement, but leaving the cortical bone intact. Copious irrigation with cooled saline during the cement extraction process is used to decrease the risk of thermal injury. Once the cement is fractured, a backhoe can be used to extract large cement fragments until the canal is cleared. A carbide tip burr is used to increase the medullary diameter of the proximal humerus to allow for improved fit of the new prosthesis. The medullary canal is then irrigated copiously and cleaned with a wire brush affixed to a drill (Figure 3).
To repair the osteotomy, Luque wires, polymer cables or sutures can be used to close the osteotomy site. In our practice, we utilize allograft fibular struts to augment the repair and close the osteotomy using polymer cables (Figure 4).
Address the glenoid side
To address the glenoid, a Fukuda retractor is placed under the glenoid, and the arm is brought into abduction and external rotation on an arm table. A 0.25-inch straight osteotome is placed at the prosthetic glenoid/bone interface and gently malleted in. A 0.5-inch straight osteotome is then placed on top of the previous osteotome and gently malleted to create a wedge effect. Further osteotomes are then stacked and malleted as necessary to gently wedge out the glenoid component. This “stacking osteotome” technique is also used to extract well-fixed glenosphere baseplates in revision reverse shoulder arthroplasty (RSA) (Figure 5).
The revision total shoulder arthroplasty or conversion to RSA components are then prepared and placed. Postoperative course consists of using an abduction sling for 1 month with arthroplasty-specific physical therapy exercises to focus first on gentle range of motion. Radiographs are taken at 2 weeks, 1 month, 2 months, 6 months and 1 year to assess for bone healing and stability of implants (Figure 6).
These technique tips for revision shoulder arthroplasty are simple and effective methods for reducing the risk of fracture and protecting bone stock. Follow-up data will be necessary to determine efficacy and long-term complications of these methods.
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- For more information:
- Mark Schultzel, MD; and John Itamura, MD, can be reached at Kerlan-Jobe Orthopaedic Clinic, 1700 E. Cesar E. Chavez Blvd. #1400, Los Angeles, CA 90012; Schultzel’s email: email@example.com; Itamura’s email: firstname.lastname@example.org.
Disclosures: Schultzel and Itamura report no relevant financial disclosures.