Abstract
Objectives:
Anterior cruciate ligament (ACL) reconstruction remains the gold standard treatment for ACL injuries. However, non-operative treatment can be suitable for certain populations. Recent observations have demonstrated the ability for the ACL to heal without surgical intervention, and to further facilitate this potential to heal the Cross Bracing Protocol (CBP) has been developed, and has subsequently received a lot of media attention, although its effectiveness is currently only supported by a single case series. This study aims to further evaluate the short-term clinical and functional outcomes of patients selected for CBP management, to further define the effectiveness of this protocol and identify predictors of success.
Methods:
This is a prospective study evaluating the short-term outcomes of patients selected for CBP management following ACL rupture, as confirmed on 3T MRI. Selection for CBP management was determined by patient suitability assessed by TC based on MRI findings, clinical criteria, and patient preference. Baseline characteristics were recorded including Tegner Activity Score, and MRI injury severity classification. At 3-months, ACL healing was graded based on MRI ACLOAS classification and those with unfavourable healing were deemed unsuccessful with CBP. 12-month evaluation included Patient Reported Outcome Measures (PROMs); Tegner Activity Score (TAS), International Knee Documentation committee (IKDC), and Lysholm Knee Scale (LKS). Additionally, ligament laxity using Dyneelax Robotic Knee Arthrometer (Genourob, Frace) and Return to Sport (RTS) functional outcomes were assessed including range of motion, strength, Y-Balance test, and Hop tests. 12-month MRI findings and recurrent injury were also observed.
Results:
133 patients were recruited between April 2024 and March 2025 who sustained an ACL rupture and deemed suitable to commence the CBP. The mean (standard deviation) baseline characteristics were determined for this cohort: age 34 (11.6), gender 65% female, side of injury 54% left, and pre-injury Tegner Score 7.2 (1.8). The ACL ruptures were further classified based on MRI findings. At 3-months 3 participants had failed to heal the ACL (ACLOAS Grade 3) and converted to surgery. At 9-months, laxity measures showed an absolute displacement difference at 200N of 1.12 mm (SD 1.0) between the healthy and injured knees and range of motion was not significantly different (p = 0.83). At 12-months, MRI grades of healing were again assessed, and PROMs were evaluated: TAS 5.7 (SD 1.9), IKDC 74.2 (SD 9.9) and LKS 93.0 (SD 9.2). At the time of analysis, 7 participants (9%) had sustained a subsequent injury and re-rupture within 12 months.
Conclusion:
The Cross Brace Protocol provides an additional non-operative option for ACL injuries and may be associated with satisfactory anatomical and functional healing for certain patient groups. The majority of patients selected as suitable for CBP demonstrated good satisfaction rates, re-rupture rates, return to pre-injury activity and ligament laxity at this short term follow up. Positive results were associated with favourable MRI injury classification at baseline and low level of pre-injury function and activity. Continued research of this novel intervention is required to observe longer term follow-up and further evaluate its effectiveness compared to ACL reconstruction and other non-operative strategies.