Joint Contact Changes With Undersized Prosthetic Radial Heads.

OBJECTIVE: To evaluate the effect of intentional undersizing of prosthetic radial head implant diameters on joint contact pressures. METHODS: Eight fresh-frozen cadaveric elbows were aligned in neutral extension and loaded with 100 N using a custom testing apparatus. Radiocapitellar contact pressures were recorded using a Tekscan thin-film pressure sensor. Prosthetic radial head replacement was performed with 2 prostheses: the Anatomic Radial Head and the Evolve Proline Radial Head prostheses. Each design was sized according to the manufacturer's recommendations and then again using 2-mm smaller radial heads. RESULTS: Average and peak pressures were significantly higher with the Evolve than the Anatomic prostheses (P < 0.03 and 0.02, respectively). Peak pressures decreased from 4.2 ± 0.5 MPa to 2.9 ± 0.3 MPa for the Anatomic Radial Heads and from 5.6 ± 0.5 MPa to 3.9 ± 0.6 MPa when the Evolve Radial Heads were undersized by 2 mm. The mean pressures of the Anatomic Radial Heads (1.4 ± 0.1 MPa) did not change significantly with undersizing (1.3 ± 0.1 MPa, P = 0.12), whereas the mean pressures of the Evolve Radial Heads (1.6 ± 0.1 MPa) were significantly reduced with undersizing (1.4 ± 0.1 MPa, P < 0.02). CONCLUSION: Both mean and peak pressures were initially high for the Evolve Radial Head sized based on the short axis diameter and were improved with further undersizing by 2 mm. Peak, but not mean, contact pressures were improved by undersizing the Anatomic prosthesis based on the long axis diameter. CLINICAL RELEVANCE: These findings support the clinical recommendation of some surgeons to undersize the Evolve prosthesis by 2-mm smaller diameter than the current manufacturer's suggestion and give reason to consider doing the same for the Anatomic prosthesis.

Surgical Treatment of Chronic Elbow Dislocation Allowing for Early Range of Motion: Operative Technique and Clinical Results.

OBJECTIVES: To describe the surgical treatment and patient outcomes of chronic elbow dislocations. DESIGN: Retrospective review. SETTING: Two tertiary referral centers. PATIENTS/PARTICIPANTS: All patients with surgically treated chronic elbow dislocation with no associated articular fracture from January 2009 to January 2015. INTERVENTION: Review of patient demographics, injury chronicity, surgical technique, and patient outcomes. MAIN OUTCOME MEASUREMENT: Clinical outcomes included elbow range of motion and complications. Radiographic outcomes included the presence of heterotopic ossification. Patient-reported outcomes included the Mayo Elbow Performance Index (MEPI) and the Summary Outcome Determination (SOD). RESULTS: Thirty-two patients with mean follow-up of 22 months (range, 13-41 months) were included. The mean dislocation duration was 6 months (range, 1-34 months). The mean preoperative range of motion was 8 degrees (range, 0-30 degrees). There were no infections or recurrent dislocations. One patient developed transient ulnar nerve palsy postoperatively. There were no cases of new or progressive heterotopic ossification. The mean postoperative extension was 31 degrees (range, 0-75 degrees), and the mean postoperative flexion was 132 degrees (range, 95-150 degrees); the mean final arc of motion was 101 degrees (range, 50-140 degrees). The mean postoperative MEPI was 93 (range, 70-100), and the mean SOD score was 9 (range, 6-10). Using the MEPI, 97% (31/32 patients) had good or excellent outcome. There was no difference in flexion/extension arc or MEPI scores between groups of elbows older and younger than 17 years or dislocations less or more than 3 months. CONCLUSION: This is the largest case series of surgically treated patients with chronic elbow dislocation. Using our surgical technique, 97% of patients had good or excellent outcome with a low complication rate. Open reduction of chronic elbow dislocation can be accomplished while permitting early motion with minimal recurrent dislocation risk. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Atypical etiology of lateral collateral ligament disruption and instability.

This report describes 2 cases of a posteroinferior capitellum impaction osteochondral injury with associated avulsion of the supinator crest resulting from a fall onto an extended upper extremity. The injury pattern in both cases was detected on x-ray films, although fully appreciated on computed tomographic imaging. Posterolateral rotatory instability occurred in both patients. One patient underwent early operative intervention (4 days postinjury) and returned to normal within 5 weeks. Surgery was delayed for the second patient (13 weeks), who initially experienced unfavorable outcomes, although stability was ultimately restored operatively. To our knowledge, this injury pattern has not previously been described as the focus of a report.