Interobserver and Intraobserver Reliability of Classification Systems for Radiographic Complications After Radial Head Arthroplasty.

PURPOSE: Although several classifications are used to assess radiographs following radial head arthroplasty (RHA), including the Popovic classification for radiolucency, the Chanlalit classification for stress shielding (SS), the Brooker classification for heterotopic ossification (HO), and the Broberg-Morrey classification for radiocapitellar arthritis, little is known about the reliability of these classification systems. The purpose of this study was to determine the interobserver and intraobserver reliability of these classifications. METHODS: Six orthopedic surgeons at various levels of training reviewed elbow radiographs of 20 patients who underwent RHA and classified them according to the Popovic, Chanlalit, Brooker, and Broberg-Morrey classifications for radiolucency, SS, HO, and RHA, respectively. Four weeks after initial review, radiographic reviews were repeated. Reliability was measured using the Fleiss kappa and the intraclass correlation coefficient. Agreement was interpreted as none (<0), slight (0.01-0.2), fair (0.21-0.4), moderate (0.41-0.6), substantial (0.61-0.8), and almost perfect (0.81-1) based on agreement among attending surgeons. RESULTS: Among fellowship-trained attending surgeons, interobserver reliability was slight for SS (Chanlalit) and the categorical interpretation of radiolucency (Popovic), fair for radiocapitellar arthritis (Broberg-Morrey) and HO (Brooker), and substantial for the ordinal interpretation of radiolucency (Popovic). Residents had a higher interobserver reliability than attending physicians when using the Brooker classification. Mean intraobserver reliability was fair for SS (Chanlalit) and the categorical interpretation of radiolucency (Popovic), moderate for HO (Brooker) and radiocapitellar arthritis (Broberg-Morrey), and almost perfect for the ordinal interpretation of radiolucency (Popovic). Trainees had higher intraobserver reliability than attending surgeons using the SS (Chanlalit) classification. CONCLUSIONS: The number of Popovic zones is reliable for communication between physicians, but caution should be taken with the Brooker, Chanlalit, Broberg-Morrey, and categorical interpretation of the Popovic classifications. All the classifications had better intraobserver than interobserver reliability. CLINICAL RELEVANCE: Reliability of classification systems for radiographic complications after RHA is less than substantial except the number of zones of radiolucency; therefore, caution is required when drawing conclusions based on these classifications.

Anatomic Radial Head Arthroplasty: The Importance of Implant Angle.

PURPOSE: Multifragmentary radial head and neck fractures not amenable to open reduction and internal fixation are usually treated with radial head arthroplasty (RHA). Although the optimal implant design is still subject to debate, anatomic designs are common. We hypothesized that positioning of the implant leading to increased radial stem angle (RSA) (angle of the RHA stem with respect to the proximal radius shaft, RSA) in anatomic RHA designs will contribute to failures. The aim of this study was to characterize the risk of RHA failure with respect to the stem angle in anatomic RHA design. METHODS: A retrospective review of patients who underwent anatomic RHA for acute fractures between 2006 and 2019 at 2 academic centers was conducted. Initial postoperative elbow radiographs were reviewed to measure RSA on the anterior-posterior and lateral views. Radiolucency, stress shielding, and radiocapitellar arthritis were also evaluated. Implant failure was defined as prosthesis removal or revision. RESULTS: Implant failure was associated with significantly larger lateral RSA than that in intact implants. Increasing stem shaft angle on a lateral radiograph was associated with decreased implant survival. Radiolucency, stress shielding, and radiocapitellar arthritis were similar between the 2 groups. CONCLUSIONS: Anatomic radial head implants are commonly used; however, the importance of prosthesis positioning, specifically that of the stem within the proximal radius, remains understudied. Higher RSA is associated with the risk of implant failure and need for revision. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.