Identifying areas of screw fixation in glenoids with severe bone loss in shoulder arthroplasty.

BACKGROUND: Severe glenoid bone loss (SGBL) poses significant technical challenges. Adequate fixation of glenoid implants may require the use of alternative screw placement. Although bone volumes for the spine and lateral pillars have previously been defined, insufficient evidence exists regarding the distribution of screw placement for fixation in such regions for cases with SGBL. The purpose of this study is to evaluate the variability of screw placement. We hypothesize that determining this variability and establishing common patterns of glenoid bone loss will allow for recommendations for preoperative planning, and implant design and selection. METHODS: An internal registry of 2 high-volume shoulder and elbow surgeons was queried, and 65 three-dimensional scapulae models exhibiting SGBL were identified. A fellowship-trained shoulder and elbow surgeon simulated the placement of two 3.5 mm × 30 mm screws, one in the scapular spine (CS) bone volume and one in the inferior column (IS) bone volume. Three orthogonal reference planes were created using anatomic reference points: the scapula trigonum, estimated glenoid center, and inferior pole. Screw positions were mapped, and deviations from the reference planes were calculated. Mutual positions of the IS to CS were also computed. Intraobserver reliability was assessed using 10 randomly selected samples. Median and 25th and 75th percentiles were reported for screw orientation distributions. Means and standard deviations were reported for screw head positions. RESULTS: We demonstrated excellent intraobserver reliability (intraclass correlation coefficients, 0.90-0.98). Fifty percent of CS were oriented 10° ± 5° of retroversion from the scapula plane, with 5° ± 5° of inclination. For IS, 50% were positioned 0° ± 4° from the scapula plane, with -33° ± 7° of inclination. The relationship of the IS with the CS was medial and posterior in 49% of cases, lateral and posterior in 45%, and lateral and anterior in 6% of cases. On average, the distance between the CS and IS heads was 25 mm ± 4 mm. DISCUSSION: For SGBL, adequate fixation of glenoid implants can be achieved by placing screws in the spine and lateral columns, with excellent reproducibility. Future implant designs should accommodate CS positioned -16° to -5° from the scapula plane, with 0° to 12° of inclination, and IS positioned -6° to 4° from the scapula plane, with -40° to -25° of inclination. Moreover, mutual screw positions suggested bone loss distributions anteriorly and inferiorly. Future implant designs should consider the potential benefits of augmentation to accommodate interscrew distances of 21-29 mm and anatomic locations of the IS relative to the CS.

Suture cerclage for stabilizing the humeral shaft during shoulder arthroplasty.

BACKGROUND: In shoulder arthroplasty, cerclage fixation techniques are used to stabilize osteotomies, fractures, and allografts. Fixation techniques including cerclage with metal and polymer cables have been described. The purpose of this study was to evaluate suture cerclage fixation of the humeral shaft during shoulder arthroplasty. MATERIALS AND METHODS: Shoulder arthroplasty cases performed from 2012-2017 by 3 fellowship-trained shoulder arthroplasty surgeons were reviewed. Cases in which suture cerclage was used for osteotomy, fracture, or allograft fixation were identified. Demographic data, indications, implant types, fixation techniques, and complications were reviewed. Postoperative radiographs were analyzed for union, component loosening, and loss of fixation. American Shoulder and Elbow Surgeons and Single Assessment Numeric Evaluation scores were collected preoperatively and postoperatively. RESULTS: A total of 27 patients (3 primary and 24 revision cases) with a mean age of 69.6 years (range, 28-88 years) were available for follow-up at a mean of 12.6 months (range, 0.8-42.3 months) postoperatively. Humeral osteotomy alone was performed in 15 cases. Allograft alone was used in 1 case. Both allograft and osteotomy were used in 6 cases. Complications occurred in 3 patients (11%), comprising 1 postoperative periprosthetic fracture and 2 prosthetic joint infections; all required further surgery. Radiographs at final follow-up showed healing of all osteotomies and fractures. No hardware failure or implant loosening occurred. The mean postoperative American Shoulder and Elbow Surgeons and Single Assessment Numeric Evaluation scores were significantly improved (α = .05) compared with preoperative scores, from 21.4 to 44.5 (P = .002) and from 26.7 to 74.1 (P < .001), respectively. CONCLUSION: Suture cerclage is safe and effective for humeral fixation in shoulder arthroplasty.

Indications and Clinical Results of Radial Head Replacement: Has Anything Changed?

Radial head fractures are common injuries comprising 1/3 of the fractures about the elbow. As a secondary valgus stabilizer of the elbow, radial head fractures can compromise elbow stability leading to long-term pain, dysfunction, and degenerative change. Furthermore, radial head fractures can be accompanied by associated injuries including ligamentous lesions that can further exacerbate elbow instability, leading to long-term sequelae. As fixation principles and technology have evolved, so has the ability to render surgical treatment for these fractures. In general, minimally displaced and some displaced fractures may be treated nonoperatively with early motion. Fractures with a block to rotation and displaced fragments with 3 or fewer fragments may be treated with open reduction and internal fixation. Comminuted fractures or those with greater than 3 fragments may be successfully treated with radial head replacement. Associated elbow instability will also influence treatment decisions.