Elbow Biomechanics, Radiocapitellar Joint Pressure, and Interosseous Membrane Strain Before and After Radial Head Arthroplasty.

Complex radial head fracture and elbow instability can be treated with radial head arthroplasty. Good clinical results have been described after this surgical treatment. However, the revision and complication rate reported in the literature is concerning. This might be due to altered kinematics after radial head arthroplasty. Eight human native elbows were examined with dynamic radiostereometric analysis and compared with a radial head arthroplasty. Translations of the radial head in the x-, y-, and z-directions relative to the humerus and the ulna were measured. The radiocapitellar joint pressure was measured using a pressure sensor. The tension within the interosseous membrane was measured using a custom-made strain gauge. After radial head arthroplasty, the radial head was displaced approximately 1.8 mm medially and 1.4 mm distally at the starting point. During unloaded flexion motion the difference in all translations between the native radial head and the radial head arthroplasty was less than 1 mm (95% confidence interval [CI] ± 0.5 mm) (p = 0.001). With loading the difference was less than 1.5 mm (95% CI ± 1.5 mm) (p = 0.001). The mean difference in radiocapitellar joint contact pressure was less than 0.30 MPa (95% CI ± 0.40 MPa) (p = 0.001) during unloaded flexion motion. There were only submillimetre kinematic changes and small changes in joint pressure and interosseous membrane tension after the insertion of a radial head arthroplasty in an experimental setting. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:510-522, 2020.

Is gain in health-related quality of life after a total hip arthroplasty depended on the comorbidity burden?

Background and purpose - Using patient-reported health-related quality of life (HRQoL), approximately 10% of patients report some degree of dissatisfaction after a total hip arthroplasty (THA). The preoperative comorbidity burden may play a role in predicting which patients may have limited benefit from a THA. Therefore, we examined whether gain in HRQoL measured with the EuroQol-5D (EQ-5D) at 3 and 12 months of follow-up depended on the comorbidity burden in THA patients Patients and methods - 1,582 THA patients treated at the Regional Hospital West Jutland from 2008 to 2013 were included. The comorbidity burden was collected from an administrative database and assessed with the Charlson Comorbidity Index (CCI). The CCI was divided into 3 levels: no comorbidity burden, low, and high comorbidity burden. HRQoL was measured using the EQ-5D preoperatively and at 3 and 12 months' follow-up. Association between low and high comorbidity burden compared with no comorbidity burden and gain in HRQoL was analyzed with multiple linear regression. Results - All patients, regardless of comorbidity burden, gained significantly in HRQoL. A positive association between comorbidity burden and gain in HRQoL was found at 3-month follow-up for THA patients with a high comorbidity burden (coeff: 0.09 (95% CI 0.02 - 0.16)) compared with patients with no comorbidity burden. Interpretation - A comorbidity burden prior to THA does not preclude a gain in HRQoL up to 1 year after THA.