Effectiveness of motor imagery in postoperative outcomes after anterior cruciate ligament reconstruction

Abstract

BACKGROUND

Motor imagery (MI) is a cognitive intervention that enhances post-operative recovery, particularly following anterior cruciate ligament reconstruction (ACLR).

AIM

To determine the effectiveness of MI-based psychological interventions on postoperative pain, psychological outcomes, functional recovery, and return to sport following ACLR.

METHODS

This systematic review evaluated the impact of MI on critical outcomes, including pain, knee function, kinesiophobia, and return-to-sport readiness in ACLR patients. A systematic search was performed in four electronic databases (PubMed, EMBASE, Scopus, Web of Science) to identify relevant studies that provided data on the effects of administering imagery techniques on the postoperative outcomes following ACLR. Eligible studies’ characteristics, patient demographics, and leading study outcomes were extracted.

RESULTS

Twelve studies including 526 individuals (266 in intervention groups, 118 in placebo groups, and 142 in control groups) were included in the qualitative synthesis. MI was most commonly administered three times per week following ACLR, with intervention durations ranging from 6 days to 24 weeks; a 24-week period was the most frequently reported. Several studies reported improvements in kinesiophobia and psychological readiness to return to sport in patients receiving imagery-based interventions compared with placebo or usual care; however, these effects were not consistent across all trials and should be interpreted with caution.

CONCLUSION

Given the psychological burden associated with ACLR, MI represents a promising adjunct to standard rehabilitation that warrants more rigorous evaluation.

Key Words: Anterior cruciate ligament; Motor imagery; Anterior cruciate ligament reconstruction; Postoperative rehabilitation; Psychological interventions; Return to sport

Core Tip: This article examined the impact of motor imagery (MI), a cognitive strategy involving the mental rehearsal of movement, on recovery following anterior cruciate ligament reconstruction. Across 12 randomized controlled trials (526 patients), MI was associated with reductions in postoperative pain and kinesiophobia (fear of reinjury) and with improved psychological readiness to return to sport in several studies, although findings were not consistently statistically significant. Integrating MI into conventional rehabilitation may offer additional psychological benefits and, in some cases, functional improvements after anterior cruciate ligament reconstruction. Larger, high-quality trials with standardized MI protocols are needed to clarify its clinical efficacy and optimal application in postoperative care.

INTRODUCTION

Rehabilitation following anterior cruciate ligament reconstruction (ACLR) is often prolonged and challenging for many patients. Although surgical intervention is effective in restoring knee stability, a substantial proportion of individuals fail to return to their preinjury level of function and report persistent psychological barriers, including lack of confidence in the reconstructed knee. Common postoperative challenges include pain, stiffness, and kinesiophobia (fear of reinjury), all of which may hinder participation in sport and activities of daily living[1,2].

Conventional postoperative rehabilitation protocols following ACLR primarily emphasize physical recovery, such as strength, range of motion (ROM), and neuromuscular control, with comparatively less attention to psychological and cognitive components of recovery. In recent years, motor imagery (MI) has been proposed as a cognitive intervention that may enhance rehabilitation outcomes. MI involves mentally rehearsing specific motor tasks without overt physical movement, activating neural networks associated with actual movement execution and potentially facilitating motor control and functional recovery while minimizing mechanical stress on healing tissues[3,4].

While MI has demonstrated beneficial effects in other areas of musculoskeletal rehabilitation, its application following ACLR remains inconsistently studied. Individual trials have reported variable effects on pain, psychological outcomes, and functional recovery, often limited by small sample sizes, heterogeneous intervention protocols, and inconsistent outcome measures. Moreover, previous systematic reviews addressing MI after ACLR were restricted by a limited number of included studies and did not incorporate more recent randomized trials or comprehensively synthesize emerging psychological outcomes such as kinesiophobia and readiness to return to sport (RTS)[3-5].

Accordingly, an updated systematic review was conducted to synthesize the current evidence on the effectiveness of MI following ACLR, with a specific focus on combining cognitive strategies, like MI, with traditional physical rehabilitation protocols holds the potential to enhance the patient’s psychological readiness, decrease the risk of subsequent injury, and improve RTS rates. By integrating newer studies and systematically addressing methodological heterogeneity, this review aims to clarify the existing evidence base and identify key gaps to inform both clinical practice and future research[6-9].

MATERIALS AND METHODS

Search strategy

This systematic review (registered in the PROSPERO database, registration No. CRD420251272773) were conducted and reported in accordance with the PRISMA 2020 statement. A completed PRISMA checklist is provided as Supplementary Table 1[10].

A systematic literature search was conducted in PubMed, EMBASE, and Web of Science from database inception to 20 July 2024. The search strategy was developed using a combination of controlled vocabulary terms [Medical Subject Headings (MeSH) in PubMed] and free-text keywords related to three core concepts: Anterior cruciate ligament pathology, surgical or rehabilitative management, and psychological or MI-based interventions.

For the population component, the following MeSH terms and keywords were used: “Anterior Cruciate Ligament” (MeSH) and free-text terms including anterior cruciate ligament (ACL) and anterior cruciate ligament. For the rehabilitation and surgical context, keywords included rehabilita, reconstruct, surgery, and treatment. For the intervention component, psychological and imagery-related terms were applied, including psychologic intervention, imagery, imagined movement, mirror therapy, movement representative technique, video, relaxation, coping, modeling, self talk, goal setting, and counseling (Supplementary Table 1).

Within each concept, terms were combined using the Boolean operator “OR”, and the three concept blocks were combined using “AND”. Searches were limited to title and abstract fields where applicable. Database-specific syntax was adapted for each platform (e.g., MeSH terms in PubMed and Emtree-aligned free-text terms in EMBASE). The full electronic search strategies for all databases are provided in Supplementary Table 1. Reference lists of all included studies were manually screened to identify additional eligible articles.

Study selection and data extraction

All titles and abstracts to identify potentially relevant articles were reviewed. Two researchers (Seyedarad Mosalamiaghili and Alireza Arvin) and independently reviewed all potentially relevant full texts for inclusion and extracted the data. Disagreements were resolved through discussion with a third investigator. The data from the studies that matched the inclusion criteria were extracted into a predefined Microsoft Excel spreadsheet (Microsoft Corp., Redmond, WA, United States): (1) Study characteristics (e.g., first author, year of publication, country, study design, inclusion and exclusion criteria, primary outcomes, findings; intervention, placebo, and control groups); (2) Participant demographics (e.g., number of participants, age (year), gender, level of activity); and (3) Main study outcomes [e.g., postoperative pain, kinesiophobia, knee laxity, knee ROM, knee strength, self-efficacy (SE), RTS, functional status]. Any conflicts were settled through discussion with a third reviewer (Salimi M).

Quality assessment

The methodological quality of all included studies was independently assessed by two reviewers (Arvin A and Mosalamiaghili S). Any disagreements were resolved through discussion, with arbitration by a third reviewer (Salimi M) when necessary. The risk of bias in randomized controlled trials was evaluated using the Cochrane Risk of Bias 2 tool[11].

Statistical analysis

A narrative synthesis was undertaken because of substantial heterogeneity in intervention types, delivery methods, outcome measures, and follow-up time points across studies. Findings were synthesized descriptively and grouped according to outcome domains (pain, kinesiophobia, psychological readiness, SE, functional outcomes, and knee strength/Laxity). Where outcomes were reported using multiple instruments, the measure most frequently reported across studies was prioritized for comparison. Risk-of-bias assessments were incorporated into the interpretation of results, and differences in outcomes were considered in light of study quality and methodological characteristics. Due to the small number of studies reporting comparable outcomes, a quantitative meta-analysis and formal assessment of publication bias were not performed.

RESULTS

Study selection

The electronic database search yielded 3517 records, including 594 from PubMed, 490 from Scopus, 1574 from EMBASE, and 859 from Web of Science. After removal of duplicates, 1952 records remained and underwent title and abstract screening, of which 1917 studies were excluded. Thirty-five articles were assessed for full-text eligibility, and 11 studies met the inclusion criteria. One additional study was identified through manual reference searching[4]. Ultimately, 12 studies[3,4,6-9,12-17] were included in the final qualitative synthesis (systematic review). The study selection process is illustrated in the PRISMA flow diagram (Figure 1).

Figure 1  The summary of study identification and selection process through PRISMA flowchart.

Study characteristics

The articles included were published between 2001 and 2023; all were randomized controlled trials. The sample sizes ranged from 12 to 101. Twelve studies comprised 526 individuals, including 266 participants undergoing the imagery interventions, 118 patients receiving the placebo, and 142 individuals in the control group (Table 1). All of the studies included in the analysis enrolled patients who had undergone isolated ACLR surgery[3,4,6-9,13-17], except for the study conducted by Almuhaya et al[12], which included patients undergoing either isolated ACLR or ACLR combined with meniscal repair. The gender distribution of participants was documented in eight studies[3,6-9,12,16,17]. Notably, in the study conducted by Almuhaya et al[12], the entire patient cohort consisted of males. The mean age of the patients ranged from 26 to 35.01. The participant demographics of the included studies are summarized in Table 1.

Table 1 Study and patient characteristics.

Ref.	Study design	Trait of participants	Number of participants	Intervention	Type of imagery	Pre-op session	Duration	Frequency	Age (year)	Sex (male/total)	Mean follow-up
Almuhaya et al[12], 2023	RCT	Cases: 13 ACLR only, 4 ACLR + MMR, 1 ACLR + both (MMR and LMR)	Cases: 16	Cases: Structured education + standard physiotherapy	Virtual interactive structured educational session via Zoom platform including a series of topics related to the surgery and the rehabilitation process prepared with pictures and graphs	No	1 week	8 five days in a week, 2 four days, 8 three or less days	26 (6)	35/35	1 week
		Controls: 12 ACLR only, 2 ACLR + MMR, 1 ACLR + LMR, 2 ACLR + both	Controls: 14	Controls: Standard physiotherapy
Lee et al[14], 2023	RCT	ACL reconstruction	Cases: 55	Cases: Smartphone app-based behavioral intervention + standard physiotherapy	A smartphone app delivering the intervention through text, pictorials, and videos on how post-surgery home-based exercises and rehabilitations will be done, behavior change techniques	No	16 weeks	NR	27.82 (8.73)	NR	16 weeks
			Controls: 41	Controls: Standard physiotherapy
Brewer et al[6], 2022	RCT	ACL reconstruction	Cases: 34	Cases: Interactive cognitive-behavioral multimedia program + standard physiotherapy	Introductory information and instructions on: (1) General information; (2) Surgery; and (3) Rehabilitation. Videos in which an orthopedic surgeon discussed the sensory and procedural aspects associated with the corresponding section of the program. Anatomical and surgical animations, video and still images of preoperative and postoperative rehabilitation exercises, video clips of former ACL reconstruction patients describing their experiences with ACL surgery and rehabilitation, a graph of pain over the rehabilitation process, and written text were among the means by which procedural and sensory information and modeling of adaptive coping responses. Links to online resources, personal accounts of and recommendations for dealing with ACL surgery and rehabilitation from former patients	Yes	24 weeks	Weekly	35.01 (11.98)	39/69	24 weeks
			Placebos: 35	Placebo: Printed educational materials + standard physiotherapy
D’Isanto et al[13], 2022	RCT	ACL reconstruction	Cases: 15	Cases: VRGI and MT + standard physiotherapy	Suggestions for imagining internal images related to the use of the affected limb in one or more functional tasks and also through the mirror box, working with the vision of a video in which, through a background voice, the subject was asked to visualize specific sports movements and gestures	No	20 weeks	3 times per week (training frequency was 5/week with a session length of 60 minutes, with MT added 3 times/week for 20-25 minutes after the end of the conventional physical therapy)	Cases: 33 (1.8)	NR	20 weeks
			Controls: 15	Controls: Physiotherapy					Controls: 32 (1.6)
Lyles et al[17], 2014	RCT	ACL reconstruction	Cases: 15	Cases: Mirror therapy + standard physiotherapy	Affected leg was placed behind a self-made mirror (non-reflecting side) and non-affected leg was placed in front of the mirror (reflecting side). Patients were instructed to observe the reflected leg into the mirror while performing the exercises and then attempt the same exercises with the involved leg	No	6 days	Once a day	Cases: 33.13 (6.99)	Cases: 10/15	6 days
			Controls: 15	Controls: Standard physiotherapy					Controls: 32.4 (5.66)	Controls: 9/15
Rhim et al[8], 2020	RCT	ACL reconstruction	Cases: 10	Cases: Modeling intervention + standard physiotherapy	Cases: Six modeling videos of semi-structured interviews and models who discussed their injury experience, expectations, and recovery and performed postoperative time-matched	Yes	24 weeks	NR	Cases: 27.1 (9.5), placebos: 32.2 (12.2), controls: 26.8 (7.9)	Cases: 9/10, placebos: 8/11, controls: 10/11	24 weeks
			Placebos: 11	Placebos: Placebo videos + standard physiotherapy	Tasks and rehabilitation exercises. Six videos were similar in length (5 minutes)
			Controls: 11	Controls: Standard physiotherapy	Reflected 6 different time points: Preoperative period, from hospitalization to 2 weeks, 2 weeks to 6 weeks, 6 weeks to 3 months, 3 months to 6 months, and 6 months and beyond following ACLR; placebos: Videos of PowerPoint slides including epidemiology of ACL injuries, anatomy of ACL, and mechanisms of ACL injury, and describing rehabilitation exercises with words
Levinger et al[7], 2017	RCT	ACL reconstruction	Cases: 10	Cases: Internet-based resource + usual rehabilitation	Video and images on ACL reconstruction, expected milestones during the recovery process, strategies to overcome distress associated with the injury, and recommended physiotherapy exercises	No	12 weeks	On a daily basis for the first week following the surgery	Cases: 32.2 (10.2)	Cases: 6/10, placebos: 4/7	12 weeks
			Placebos: 7	Placebos: Restricted access to internet-based resource + usual rehabilitation				Three times per week for weeks 2-3 following the surgery	Placebos: 28.5 (9.1)
								Once a week for weeks 4-12 following the surgery
Zaffagnini et al[9], 2013	RCT	ACL reconstruction	Cases: 51	Cases: Therapeutic vision videos + standard physiotherapy	Cases: Art video producing therapeutic insight	No	8 weeks	3 times per week	33 (17)	80/101	12 weeks
			Placebos: 50	Placebos: Videos of unfavorable information + standard physiotherapy	Placebos: Art video with an insight unfavorable to the psychological recovery
Maddison et al[16], 2012	RCT	ACL reconstruction	Cases: 13	Cases: Mental rehearsal of rehabilitation goals + standard physiotherapy	Nine individual sessions of mental rehearsal of activities to achieve physical rehabilitation goals including cognitive, motivational, and healing imagery; cognitive imagery was used to rehearse rehabilitation exercises, using both visual and kinaesthetic modalities. Motivational imagery was used to set goals, control arousal levels, and increase self-confidence. Healing imagery was used to imagine the physiological processes taking place during rehabilitation	No	24 weeks	NR	34.86 (8.84)	13/21	24 weeks
			Controls: 8	Controls: Standard physiotherapy
Lebon et al[4], 2012	RCT	ACL reconstruction	Cases: 7	Cases: Imagining muscle contractions + standard physiotherapy	3 blocks of 10 imagined contractions, with a 10-second rest period between rehearsals and 2-minute rest period between blocks	No	5 weeks	Every 2 days	28.5 (5)	NR	5 weeks
			Placebos: 5	Placebos: Neutral mental task (crossword or calculation) + standard physiotherapy
Maddison et al[15], 2006	RCT	ACL reconstruction	Cases: 30	Cases: Coping-model video + standard physiotherapy	Two coping model videos of edited interviews and models performing rehabilitation exercises; first video pre-op to 2 weeks post-op (9-minute) and second video 2 weeks to 6 weeks post-op (7-minute)	Yes	6 weeks	NR	30	NR	6 weeks
			Controls: 28	Controls: Standard physiotherapy
Cupal and Brewer[3], 2001	RCT	ACL reconstruction	Cases: 10	Cases: Mental rehearsal of rehabilitation goals + standard physiotherapy	Videos of patient’s arthroscopic procedure, facilitating knee flexibility and ROM, edema reduction, knee strength, position sense, anxiety reduction, anatomical and neurological mental comparison	No	24 weeks	Every 2 weeks	28.2 (8.2)	16/30	24 weeks
			Placebos: 10	Placebos: Peaceful scene imagery + attention, encouragement, and support + standard physiotherapy
			Controls: 10	Controls: Standard physiotherapy

MMR: Medial meniscus repair; LMR: Lateral meniscus repair; VRGI: Virtual reality-guided imagery; MT: Mirror therapy; RCT: Randomized controlled trial; ACL: Anterior cruciate ligament; ACLR: Anterior cruciate ligament reconstruction; ROM: Range of motion; NR: Not reported.

Six studies compared the intervention group with the placebo groups[3,4,6-9], while eight compared the intervention group with controls (Table 1)[3,8,12-17]. Research by Rhim et al[8] and Cupal and Brewer[3] contrasted the intervention groups with placebo and control groups (Table 1).

The frequency of intervention administration was documented in eight studies[3,4,6,7,9,12,13,17] with three-times-per-week schedule being the most commonly reported frequency, appearing in four of the studies[7,9,12,13]. With regard to the length of the program, the 24-week treatment period was the longest and most reported duration, having been found in four investigations[3,6,8,16]. The shortest treatment period, however, was found in the study by Lyles et al[17], which lasted only six days. The presence of preoperative treatment sessions was reported in three studies[6,8,15]. The mean follow-up duration ranged between 6 days to 24 weeks. Detailed information about the intervention characteristics is presented in Table 1.

Outcome measurements

Postoperative pain: A total of three articles compared the postoperative pain between the intervention and control groups[3,13,17] (Table 2). Quantitative analysis was impractical due to the disparate scales employed for reporting pain in the articles. However, studies by D’Isanto et al[13], Cupal and Brewer[3], and Lyles et al[17], all revealed significantly improved postoperative pain in the intervention group in comparison to control individuals (P value = 0.023, < 0.05, and 0.0018; respectively).

Table 2 Outcome evaluations between intervention and control groups.

Ref.	Measured outcomes	Results
Almuhaya et al[12], 2023	Kinesiophobia (TSK)	Improved TSK (P = 0.026) and ACL-RSI (P = 0.009) in cases than controls, no significant difference in IKDC (P = 0.42) between groups
	Return to sport (ACL-RSI)
	Functional status (IKDC)
Lee et al[14], 2023	Knee strength (biodex isokinetic dynamometer)	No significant difference in muscle strength (P = 0.25 to 0.96), knee laxity (P = 0.96), and subjective knee evaluation (P = 0.99) between groups
	Knee laxity (KT1000)
	Functional status (IKDC)
D’Isanto et al[13], 2022	Pain (VAS score)	Greater psychological readiness (P < 0.01) and lower postoperative pain in cases than controls
	Psychological readiness (ACL-RSI)
Lyles et al[17], 2014	Pain (VAS score)	Improved postoperative pain (P = 0.0018), AROM (P = 0.0004), PROM (P = 0.0011), and Lysholm score (P = 0.044)
	ROM (AROM and PROM in flexion)
	Functional status (Lysholm)
Rhim et al[8], 2020	Kinesiophobia (TSK)	No significant difference in self-efficacy (P = 0.808), return to sport (P = 0.574), kinesiophobia (P = 0.888), and KOOS subscales (P = 0.236 to 0.916) between groups
	Return to sport (ACL-RSI)
	Self-efficacy (K-SES)
	Functional status (KOOS)
Maddison et al[16], 2012	Self-efficacy (AISEQ)	Improved postoperative knee laxity (P < 0.05) favoring the intervention
	Knee strength (180/second, 60/second)	No significant difference for knee strength for extension at 180/second (P = 0.67) or 60/second (P = 0.48)
	Knee laxity (KT1000)	Fairly stable self-efficacy between weeks 6 to weeks 12 in cases than controls
Lebon et al[4], 2012	Preoperative perception of pain (0-100 scale)	Improved crutches (P < 0.01), walking (P = 0.01), and exercise (P < 0.05) SE in cases than controls only at predischarge, better IKDC 6 weeks postop, less crutches use time in cases than controls (P < 0.01)
	Preoperative anxiety (STAI)
	Self-efficacy (CSE, WSE, ESE)
	Functional status (IKDC subjective and objective)	No significant difference in preoperative anxiety reduction, preoperative perception of pain reduction (P = 0.52), and postoperative ROM (P = 0.36) between groups
	ROM by goniometry
	Crutches use time
Maddison et al[15], 2006	Pain (0-10 scale)	Improved pain in cases than controls (P < 0.05). Greater post-op knee strength in cases than controls (P < 0.02). Reduced re-injury anxiety in cases than controls (P < 0.05)
	Reinjury anxiety (0-10 scale)
	Knee strength (cybex 6000)
	Isokinetic dynamometer)

TSK: Tampa scale of kinesiophobia; ROM: Range of motion; AROM: Active range of motion; PROM: Passive range of motion; K-SES: Knee Self Efficacy Scale; STAI: State-Trait Anxiety Inventory; CSE: Crutches self-efficacy; WSE: Walking self-efficacy; ESE: Exercise self-efficacy; AISEQ: Athletic Injury Self-Efficacy Questionnaire; KOOS: Knee Injury And Osteoarthritis Outcome Score; ACL-RS: Anterior cruciate ligament-return to sport after injury; QOL: Quality of life; IKDC: International knee documentation committee; EMG: Electromyography; VAS: Visual analogue scale.

Comparing the MI and placebo groups, three studies documented the postoperative pain (Table 3)[3,4,6], of which studies by Brewer et al[6] and Cupal and Brewer[3] presented a significantly diminished postoperative pain in the imagery group in comparison to the placebo group (P value = 0.02 and < 0.05, respectively). However, the study by Lebon et al[4] found no significant difference in postoperative pain scores between groups (P value > 0.05).

Table 3 Outcome evaluations between intervention and placebo groups.

Ref.	Measured outcomes	Results
Brewer et al[6], 2022	Pain (NRS)	Lower postoperative pain (P = 0.02), lower kinesiophobia (P = 0.77), improved postoperative symptoms (P = 0.002) in cases than controls
	Kinesiophobia (TSK)	No significant difference in flexion ROM (P = 0.99), extension ROM (P = 0.18), and knee laxity (P = 0.09) between groups
	Subjective symptoms (KOS-SAS)
	Knee laxity (KT1000)
	ROM (flex and ext)
Rhim et al[8], 2020	Kinesiophobia (TSK)	No significant difference in self-efficacy (P = 0.808), return to sport (P = 0.574), kinesiophobia (P = 0.888), and KOOS subscales (P = 0.236 to 0.916) between groups
	Return to sport (ACL-RSI)
	Self-efficacy (K-SES)
	Functional status (KOOS)
Levinger et al[7], 2017	Self-efficacy (K-SES)	No significant difference in KOOS subscales (P = 0.07-0.76), self-efficacy subscales (P = 0.42 and 0.71), kinesiophobia (P = 0.46), fear of activity (P = 0.96) between groups
	Functional status (KOOS)
	Kinesiophobia (TSK)
	FABQ
Zaffagnini et al[9], 2013	QOL (mental and physical SF-36)	Improved subjective IKDC (P = 0.047), TKS (P = 0.0141) and time to crutches discharge (P = 0.0012). No significant difference in Tegner score, and SF-36 mental and physical status between groups
	Kinesiophobia (TSK)
	Functional (subjective and objective IKDC, Tegner)
	Crutches use time
Lebon et al[4], 2012	Isometric activation of the medial musculature (EMG during maximum knee extension)	Greater postoperative musculature activity in cases than controls (P = 0.02). No significant difference in postoperative pain, ROM, effusion reduction, thigh circumference, LEFS score (P > 0.05) between groups
	Pain (VAS score)
	Ability to perform daily activities with lower extremity injury using the LEFS
	Magnitude of surgical effusion and atrophy by the circumference of the knee above the kneecap and circumference of the thigh 15 cm above the kneecap
	Knee ROM (goniometry)
Cupal and Brewer[3], 2001	Pain (0-10 scale)	Improved pain in cases than placebos (P < 0.05). Reduced re-injury anxiety in cases than placebos (P < 0.05). Greater post-op knee strength in cases than placebos (P < 0.003)
	Reinjury anxiety (0-10 scale)
	Knee strength (cybex 6000)
	Isokinetic dynamometer

SF-36: Short form 36; NRS: Numeric rating scale; TSK: Tampa scale of kinesiophobia; KOS-SAS: Knee Outcomes Survey - Sports Activities Scale; ROM: Range of motion; K-SES: Knee Self Efficacy Scale; LEFS: Lower Extremity Functional Scale; KOOS: Knee Injury And Osteoarthritis Outcome Score; FABQ: Fear-Avoidance Beliefs Questionnaire; ACL-RSI: Anterior cruciate ligament-return to sport after injury; QOL: Quality of life; IKDC: International knee documentation committee; EMG: Electromyography; VAS: Visual analogue scale.

Postoperative kinesiophobia: Studies by Rhim et al[8] and Almuhaya et al[12] provided data on postoperative kinesiophobia (as measured by the Tampa Kinsiophobia Scale), comparing the imagery and control groups (Table 2). The study by Almuhaya et al[12] noted improved kinesiophobia following surgery in patients who received MI in comparison to the control group (P value = 0.026). In contrast, the study by Rhim et al[8] reported no significant difference between the study groups. Most studies reported a reduction in kinesiophobia following imagery-based interventions, although effect magnitude varied.

Postoperative knee laxity: Studies by Lee et al[14] and Maddison et al[16] provided data on postoperative knee laxity comparing case and control groups (Table 2). The study by Lee et al[14] found no significant difference in postoperative knee laxity between study groups (P value = 0.96). However, Maddison et al[16] reported significantly improved knee laxity after surgery in the imagery group compared to the controls (P value < 0.05).

Only one study by Brewer et al[6] compared postoperative knee laxity between patients who watched imagery videos and those who received placebo videos which reported no significant difference regarding the postoperative knee laxity between the two groups (P value = 0.09) (Table 3).

Postoperative knee ROM: Two studies compared the postoperative knee ROM between the intervention and control groups (Table 2)[15,17]. The study by Lyles et al[17] reported significant improvements in postoperative active and passive knee ROM in the imagery group in comparison to the control group (P value = 0.0004 and 0.0011, respectively). However, the study by Maddison et al[15] found no significant difference in postoperative knee ROM between the intervention and control groups (P value = 0.36).

Studies by Brewer et al[6] and Lebon et al[4] provided data on postoperative knee ROM in the imagery group compared to the placebo group, of which both presented no significantly improved postoperative knee ROM in patients who received imagery videos in comparison to the placebo group (P value > 0.05) (Table 3).

Postoperative strength: A total of three articles compared the postoperative knee strength between the intervention and control groups[3,14,16] (Table 2). Meta-analysis was unreasonable to conduct due to the heterogeneity in reported variables. Cupal and Brewer[3] showed significantly improved knee strength, which was measured with a Cybex 6000 isokinetic dynamometer, an instrument that assesses maximal torque during concentric-eccentric movements of a limb, following the surgery in imagery groups compared to the controls (P value < 0.02). However, studies by Lee et al[14] and Maddison et al[16] declared no significant difference in postoperative knee strength between the study groups (P value > 0.05).

Cupal and Brewer[3] study compared postoperative knee strength between patients who received imagery videos and those in the placebo group (Table 3). The study reported significantly higher knee strength in the imagery group compared to the placebo group (P value < 0.003).

Postoperative SE: Three studies provided information on comparing postoperative SE between the imagery and control groups[8,15,16] (Table 2). However, the variety of SE measurement scales prevented us from the conduction quantitative analysis. The study by Maddison et al[15] found improved SE in walking, using crutches, and exercise performance in patients who underwent imagery techniques than those who received only a standard physiotherapy program (P value = 0.01, < 0.01, < 0.05; respectively). Another study by Maddison et al[16] reported relatively stable SE between postoperative weeks 6 to weeks 12 in the imagery group than controls. Nonetheless, the survey by Rhim et al[8] represented no significant difference in postoperative SE between the study groups (P value = 0.808).

Two studies by Levinger et al[7] and Rhim et al[8] evaluated postoperative SE between the intervention and placebo groups. They exhibited no significant difference in postoperative SE between study groups (P value = 0.808, and P value = 0.42 and 0.71 for SE subscales, respectively) (Table 3).

Postoperative psychological readiness

Study by Rhim et al[8] compared postoperative RTS between imagery and placebo groups, which reported no significant difference in postoperative Anterior Cruciate Ligament-RTS after Injury (ACL-RSI) scale between the study groups (P value = 0.574) (Table 3).

Functional status

Among the studies that compared intervention and control groups, the International Knee Documentation Committee (IKDC) score was assessed in three studies[12,14,15] (Table 2), showing no significant improvement postoperatively in two studies (P value = 0.42 and 0.99)[12,14], while one study reported a better score at 6 weeks post-operation[15]. The Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales was examined in the study by Rhim et al[8] indicating no significant difference between groups (P value = 0.236 to 0.916). Additionally, the Lysholm score was evaluated in one study[17], demonstrating a significant improvement following surgery in the imagery group compared to the controls (P value = 0.044).

In studies comparing interventions with placebo groups, two investigations evaluated the KOOS score and found no significant differences[7,8]. Only Zaffagnini et al[9] evaluated IKDC and Tegner scores, showing a substantial improvement in IKDC (P value = 0.047) but no significant change in postoperative Tegner scores after treatment (Table 3). Due to the limited number of studies and heterogeneity of outcomes, a meta-analytic synthesis and formal assessment of publication bias were not performed.

DISCUSSION

This article evaluated the effects of mental imagery-based and other psychological interventions on postoperative outcomes following ACLR. Across the included randomized controlled trials, a wide range of interventions was examined, including MI, guided imagery, mirror therapy, educational and multimedia programs, and web-based or modeling approaches. Outcomes varied substantially and included postoperative pain, kinesiophobia, SE, psychological readiness to RTS, knee function, and strength. Intervention timing and duration also differed considerably, ranging from brief preoperative exposure to programs extending several months into postoperative rehabilitation.

Beyond physical impairment, ACL injuries are associated with substantial psychological consequences. Previous research has shown that only approximately 55% of athletes RTS after ACLR, often at a reduced level compared with preinjury status[18,19]. Psychological factors, particularly fear of reinjury and kinesiophobia, are common after ACL reconstruction and have been shown to hinder RTS, alter knee biomechanics, and potentially increase the risk of reinjury[20] targeted psychological interventions may therefore play a critical role in improving both psychological and functional recovery after ACLR[21].

Imagery-based interventions may help reduce fear of reinjury and postoperative discomfort. Addressing psychological factors during early rehabilitation may alleviate pain and improve ROM, while continued application throughout later rehabilitation phases may remain beneficial. However, findings across studies were not entirely consistent. Lebon et al[4] reported no significant benefit of MI, potentially due to the use of strong analgesic therapy during the early postoperative period, which may have influenced patients’ perception of imagery effects. Nevertheless, substantial evidence supports the role of imagery in pain reduction, both in ACLR and in sports-related injuries more broadly[22,23] with additional studies in this review reporting similar findings[3,6,13,17].

The proposed mechanism underlying pain reduction through MI and mirror therapy relates to modulation of sensory-motor integration within the central nervous system[24]. These techniques may reduce incongruence between motor intention and sensory feedback, which is thought to contribute to pain perception[25]. By influencing cognitive and emotional processing of pain, such interventions may alter the subjective pain experience[26]. Several studies reported reductions in pain across different mental training techniques suggests a shared underlying mechanism[27], although mirror therapy does not appear to provide superior immediate analgesia compared with MI alone[28].

Psychological readiness to RTS represents another important outcome following ACLR. Although many patients recover adequate physical function, a considerable proportion do not resume sport participation[29]. At the amateur level, approximately one-third of female football players fail to RTS, and those who do remain at increased risk of reinjury, particularly to the contralateral limb[30]. Across the included studies, findings for postoperative ACL-RSI were mixed, with some trials reporting improvement and others showing little or no change. Rhim et al[8] assessed multiple psychological measures and reported a significant effect only for knee SE at six months postoperatively. The inclusion of a placebo group in their study may partly explain discrepancies with other trials, as controlling for the effect of receiving video-based content - irrespective of its psychological focus - is important when evaluating modeling interventions[31]. While placebo-controlled designs enhance methodological rigor, they may not always be essential in future trials with limited resources[8,32].

Mirror therapy and structured educational interventions also demonstrated potential benefits. D’Isanto et al[13] reported improved Sport after Injury Scale scores in players receiving mirror therapy, accompanied by reduced pain and enhanced SE. Similarly, Almuhaya et al[12] found that structured educational sessions during rehabilitation significantly improved ACL-RSI scores and reduced kinesiophobia. These findings suggest that combining imagery techniques with educational components may further enhance psychological readiness during rehabilitation. Additionally, technology-based delivery methods, such as interactive multimedia programs, may improve accessibility and engagement, as demonstrated by Brewer et al[6].

Evidence regarding the effects of psychological interventions on biomechanical and functional outcomes remains mixed. Some studies reported improvements in knee laxity[16,33], while others found no significant differences[6,14], reflecting the ongoing controversy in the literature[34]. Psychological factors may influence knee laxity indirectly through rehabilitation adherence and neuromuscular control[35]. However, recovery outcomes are also affected by numerous moderators, including rehabilitation protocols, surgical factors, injury severity, and individual patient characteristics[36]. Short follow-up periods may further limit the ability to detect meaningful changes in objective clinical outcomes[14]. Longer follow-up durations may better capture recovery trajectories as patients progress to higher-intensity rehabilitation phases[37].

Functional outcomes were assessed using various instruments, including the IKDC, KOOS, and Lysholm scores. Each tool captures different dimensions of knee function, with the KOOS and Lysholm scores demonstrating high responsiveness over time[38-40], while the IKDC remains the most commonly used patient-reported outcome measure in ACL research due to its reliability and validity[41]. Results across studies were inconsistent, with some reporting short-term improvements[3,15,17], and others showing no significant difference[14]. Variability in intervention type and outcome selection likely contributed to these mixed findings.

Limitations and future directions

Only 2 studies had more than 50 participants in our included studies, indicating a clear limitation in sample size across the reviewed literature. Additionally, 3 out of 12 studies used remote interventions while the rest relied on in-person methods[6,7,14]. Furthermore, the gender distribution was only reported in eight studies, and one study included only male participants, introducing potential bias. Only a small number of studies reported the same outcome measures, which limited comparability across trials.

The studies varied significantly in their intervention protocols, ranging from six days to 24 weeks, with most lacking follow-up with patients beyond 24 weeks, limiting the understanding of long-term outcomes. Differences in interventions, timing, and delivery likely contributed to variability in study findings. Another methodological limitation is the reliance on self-report measures, which may introduce bias, such as self-serving tendencies. Future research should consider integrating objective measures, such as clinic attendance or implicit association tests, to capture more objective data. Additionally, the lack of detailed data on intervention adherence, such as the frequency and duration of usage in remote interventions, limits the ability to evaluate the true impact of these methods. Finally, important confounding factors, such as the severity of ACL tears, socio-economic status, and leg dominance, were not consistently accounted for across the studies, which may have influenced the results. Larger sample sizes and better control of these variables are essential for future research to fully understand the effectiveness of psychological interventions in ACL reconstruction rehabilitation.

CONCLUSION

This article suggests that psychological interventions - particularly those incorporating MI - may help reduce postoperative pain following ACL reconstruction. However, evidence for effects on kinesiophobia, SE, functional recovery, and RTS remains inconsistent across studies. Interpretation is limited by small sample sizes, variability in intervention protocols, and short follow-up durations. Larger, well-designed randomized trials with standardized outcome measures are needed to clarify the role of psychological interventions in ACL rehabilitation.