RESUMEN
Background: Superior inclination of the base plate in reverse shoulder arthroplasty (RSA) is underestimated and may lead to major setbacks in terms of functional outcomes due to the altered biomechanics. Joint instability, scapular notching, and loosening of the glenoid component are considered the most serious sequelae. Therefore, a thorough preoperative radiological assessment of the affected shoulder joint and customized design of the prosthesis according to the glenoid morphology are decisive and directly correlated to the outcome. In this article, we propose a simple radiographic technique to assess the inclination of the glenoid preoperatively, which identifies the need for intraoperative correction. Materials and Methods: One hundred inconspicuous shoulder radiographs were included in the control group (CG) to define the normal ranges of the base plate orientation angle (BOA) and the base plate correction angle (BCA). Further, both angles were measured on 2-dimensional (2D) computed tomography scans of patients with proximal humerus fractures as well as radiographs, 2D and 3-dimensional (3D) computed tomography scans of patients with cuff tear arthropathy who underwent RSA between 2018 and 2021. The interobserver reliability among three independent testers was evaluated by calculating the intraclass correlation coefficient. In cuff tear arthropathy cases, the BOA and BCA measurements on different imaging modalities were compared using the Wilcoxon test. Possible variations of both angles' values based on glenoid erosion types, according to the Favard classification, were also investigated. Results: Regardless of the imaging modality used, the interobserver reliability was excellent among three independent observers. In the CG, the mean BOA and BCA values were 118° ± 6° and 17° ± 5°, respectively. The mean corrected BOA values of the CG and fracture group were 136° ± 5° and 140° ± 5°, respectively. In contrast to the BCA values, the BOA measurements on radiographs showed a statistically significant difference compared to those obtained on 2D- and 3D scans in the cuff arthropathy group. Further, both angles' values varied according to the extent and location of the glenoid erosion. The lowest mean BOA and highest mean BCA values were observed in cases with Favard glenoid type E3. Conclusions: The BOA and the BCA are reliable tools proposed to aid in precisely positioning the glenoid component in RSA in the preoperative setting. Whereas, the BOA determines the inclination of the inferior glenoid segment, the BCA represents the extent of correction required to obtain a neutral inclination of the base plate. Glenoid type E3 of the Favard classification with superior wear is particularly susceptible to base plate superior tilt.
RESUMEN
Objectives: The radiological measurement of the Böhler angle (BA) and the critical angle of Gissane (CAG) is used not only to diagnose and corroborate the suspicion of the presence of calcaneal fractures but also to assess the prognosis of different injury patterns and to evaluate the operative reduction of calcaneal fractures. Notwithstanding, many previous studies indicated the poor intra- and interobserver reproducibility of both angles. In this retrospective study, we present the subtalar calcaneal angle (SCA) as an additional diagnostic tool -to BA and CAG-which can be applied on pre- and postoperative radiographs to assess calcaneal fractures involving the posterior facet. Design: Retrospective Study. Methods: Two retrospective groups were established, a 'CF-group' including radiographs of patients diagnosed with a calcaneal fracture and underwent operative treatment in the authors' traumatology department, and a 'control group' with 50 lateral calcaneal radiographs clear of skeletal lesions. Initially, the SCA, BA, and CAG were measured in both groups by three examiners. Those measurements were repeated one month later. The intra- and intertester reliabilities of all three angles were tested by determining the intraclass correlation coefficient (ICC). A paired t-test was used to prove the statistically significant difference between the SCA values for the pre- and postoperative groups, while the significant difference between the SCA values for the control and preoperative groups was tested through an independent-samples t-test. Results: The intra- and interobserver reliability of the SCA and the BA was in close proximity. The values of the SCA in both the control and postoperative groups were significantly different compared to the measurements of the preoperative group. The CAG showed poor intertester reliability. Conclusion: The subtalar calcaneal angle is a new instrument with proven reliability in estimating the prognosis of displaced calcaneal fractures and the postoperative alignment of the posterior facet. Level of clinical evidence: Diagnostic, Level III.
