**1. Introduction**

The treatment of anterior cruciate ligament (ACL) rupture in the physically active population is often surgical. Patients treated with ACL reconstruction usually aim to return to sport activities they practiced before injury [1–3].

However, a significant number of patients ranging between 37% and 56% are not able to return to sport at pre-injury level [4]. Reasons for that include the persistence of knee strength and neuromuscular deficits, kinesiophobia, and fear of re-injury [5]. Increased risks of re-rupture have been reported within the first two years after surgery, especially in

**Citation:** Legnani, C.; Del Re, M.; Viganò, M.; Peretti, G.M.; Borgo, E.; Ventura, A. Relationships between Jumping Performance and Psychological Readiness to Return to Sport 6 Months Following Anterior Cruciate Ligament Reconstruction: A Cross-Sectional Study. *J. Clin. Med.* **2023**, *12*, 626. https://doi.org/ 10.3390/jcm12020626

Academic Editor: Yuichi Hoshino

Received: 16 December 2022 Revised: 4 January 2023 Accepted: 6 January 2023 Published: 12 January 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

the youngest patients [6,7]. For these reasons, in an attempt to reduce risk factors and to determine the appropriate timing for resuming sports activities, test batteries have been developed. These include but are not limited to jumping abilities assessment, strength tests, and psychological readiness scoring systems [8–11]. Tests measuring muscular power and reactivity through vertical jump are demonstrated to be reliable instruments and useful predictors for the return to sports [11,12]. Horizontal hop tests have been widely adopted to detect functional asymmetries between limbs [13,14], although their usefulness has been questioned as they are demonstrated to overestimate the involved limb's function following ACL surgery [15,16]. Investigating the relationship between functional capacity and psychological readiness is of paramount importance when planning sport resumption following ACL reconstruction [9]. Therefore, vertical jump tests have been advocated to better analyze knee biomechanics, thus identifying lower limb asymmetries more accurately, and give a more reliable prediction on the return-to-sport ability [11].

The ACL–Return to Sport after Injury scale (ACL-RSI) is considered a reliable tool to assess psychological readiness to return to sport after ACL surgery [17,18]. It has been demonstrated that patients with lower ACL-RSI scores are at higher risk for ACL re-rupture [19], and recently much emphasis is given to the recovery of psychological responses as a criterion used to clear athletes to return to sport following ACL reconstruction.

The aim of this study was to prospectively assess outcomes of athletes who had undergone primary ACL reconstruction at 6 months after surgery, and to evaluate whether psychological readiness affects functional and clinical results as well as jumping ability. The hypothesis was that athletes' psychological readiness is strictly related to jumping performance.
