Preoperative serum calcium could be a prognostic factor for surgical treatment of recurrent patellar dislocation: a retrospective study

(2022) 23:578 Qiao et al. BMC Musculoskeletal Disorders https://doi.org/10.1186/s12891-022-05527-y Open Access RESEARCH Preoperative serum calcium could be a prognostic factor for surgical treatment of recurrent patellar dislocation: a retrospective study Yi Qiao† , Zipeng Ye† , Junjie Xu† , Xiuyuan Zhang , Jiebo Chen , Caiqi Xu , Song Zhao* and Jinzhong Zhao*    Abstract Background: Surgical treatment for recurrent patellar dislocation (RPD) could yield good outcomes. While, unsatisfactory recovery still exists in some cases. For all prognostic factors, serum biomarkers have rarely been investigated. This study aimed to evaluate the prognostic value of preoperative serum calcium level, a widely used serum biomarker, in surgical treatment for RPD. Study design: Retrospective study. Methods: Ninety-nine patients with RPD were enrolled in the study. Preoperative serum calcium was acquired from routinely tested blood 1 day prior to operation. Demographic data, characteristics of RPD, postoperative functional outcomes were obtained. The association between preoperative calcium and postoperative functional outcomes (Kujala, Lysholm, Tegner, IKDC and KOOS score) was determined by correlation analysis and multivariate linear regression analysis. Poor recovery was determined as Kujala score below 80. The receiver operating characteristic (ROC) curve was used to assess the prognostic value of preoperative calcium. Results: Patients were followed up for a mean period of 2.45 ± 1.33 years. All clinical scores showed significant improvement at the latest follow-up. Correlation and multivariate linear analyses indicated that serum calcium level was an important factor related with the prognosis of surgical treatment for RPD. According to the ROC curve, the cut-off value for preoperative calcium was 2.225 mmol/L. The clinical outcomes of patients with a preoperative blood calcium < 2.225 mmol/L was significantly worse than that with a higher calcium level. The correspondent sensitivity was 0.812 with a specificity of 0.633. Conclusion: Operative treatment for RPD achieved good results, while in some cases the functional scores remain inferior. As a serum biomarker, preoperative calcium could be prognostic for outcomes after surgical treatment for RPD. Keywords: Recurrent patellar dislocation, Prognosis, Calcium, Serum biomarker † Yi Qiao, Zipeng Ye and Junjie Xu contributed equally to this work. *Correspondence: ; Department of Sports Medicine, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, 600 Yishan Road, Shanghai 200233, China Introduction Recurrent patellar dislocation (RPD), a common issue plaguing adolescent, is associated with various anatomical factors including soft tissue and bony abnormalities [1–3]. Medial patellofemoral ligament (MPFL) reconstruction © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Qiao et al. BMC Musculoskeletal Disorders (2022) 23:578 combined with or without tibial tubercle (TT) transfer has been widely employed to treat recurrent patellar dislocation and usually yields favorable outcomes [4]. However, inferior postoperative outcomes are still presented in some cases and reoperation may be required [5]. Identification of prognostic factors may help classify patients for whom postoperative outcome is more likely to be inferior and pay special attention to improve these patients’ recovery [6]. Numerous factors have been investigated for recurrent patellar dislocation, including age, sex, patella alta, trochlear dysplasia, J-sign and various surgical techniques [7, 8]. Multiple researchers have developed predictive models for recurrent instability by combining these individual factors in different ways [9, 10]. To date, these models remain complex and require multiple imaging examinations, imposing a burden on patients’ cost. Postoperative recovery is affected by metabolic processes associated with inflammation [11], collagen or bone turnover [12], which may have a role in predicting the prognosis. Biomarkers, as a manifestation of these metabolic processes, have a potential utility in developing early diagnoses and evaluating prognosis [13]. Compared with other methods, biomarkers can be collected relatively easily form serum or urine and may be less costly. The identification of such biomarkers could better assist practitioners in assessing the prognosis of patients undergoing operation. As a widespread secondary messenger within multiple intracellular signaling pathways, calcium is involved in the bone turnover and a myriad of vital cellular activities including proliferation, motility and apoptosis, suggesting that calcium plays an important role in tissue regeneration and parenchymal function across the body [14]. In recent years, serum calcium level has been used to help determine the prognosis of cardiovascular event, cognitive decline and cancer [15–17]. Therefore, the aim of this study was to evaluate the association between preoperative serum calcium level and the clinical outcome after surgical treatment for recurrent patellar dislocation. Our assumption was that the serum calcium level could be a prognostic factor of recurrent patellar dislocation. Methods Study design and participants This was a single-center, retrospective study. It was registered in the Chinese Clinical Trial Registry (ChiCTR2100 052216) in 22/10/2021. The methods were performed in accordance with the relevant guidelines and regulations. We retrospectively studied the patients that were consecutively enrolled in the institutional database program of RPD from January 2017 to October 2020. The inclusion Page 2 of 8 criteria were closed epiphysis, more than 2 episodes of dislocation or 1 episode of dislocation plus multiple episodes of instability (lateral excursion of the patella), and a tibial tubercle-trochlear groove (TT-TG) distance > 15 mm. The exclusion criteria were concomitant ligament injuries (except MPFL), pre (...truncated)