Treatment strategies for concomitant ligament injury in anterior cruciate ligament-injured athletes, a narrative review

Introduction

Background

Multiligament knee injuries (MLKIs) are defined as injury to two or more of the four major knee ligaments: anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and posteromedial corner (PMC), and the lateral collateral ligament (LCL) and posterolateral corner (PLC). While high-energy MLKIs are well-described in orthopedic trauma literature, there is minimal literature evaluating incidence and outcomes of MLKIs in athletes. Athletes are unique as returning to functional return-to-play (RTP) puts the repaired or reconstructed ligaments under the same constraints which caused prior injury. MLKIs account for approximately 0.02–0.20% of all orthopedic injuries (1). In high-level athletes, these injuries are sports specific and can be collision based or relatively higher energy, but frequently are lower energy and may occur as a result of axial loading and rotation with or without contact. These are typically much different injuries than those seen with a frank knee dislocation in a polytrauma patient from a high-speed motor vehicle collision.

The management of MLKIs in athletes can be challenging. The unique factors encountered in this population include pressure to RTP, returning to the same high level of play, and the impact of injury on career longevity. While surgical management is the mainstay of treatment, considerations for timing, graft choice, and management of concomitant injuries add to the complexity of surgical planning. Additionally, postoperative management with rehabilitation protocols and psychosocial support are important factors contributing to RTP.

The purpose of this review is to collate the available evidence regarding the treatment of MLKIs in an athletic population, identify key considerations relevant to surgical decision-making, and elucidate factors that impact functional recovery and RTP success. This review will also attempt to identify areas where the literature is lacking and potential opportunities for future research unique to this patient population. We present this article in accordance with the Narrative Review reporting checklist (available at https://aoj.amegroups.com/article/view/10.21037/aoj-25-28/rc).

Methods

This narrative review employed a structured approach to provide a thorough and transparent summary of the most relevant evidence (Table 1). A systematic search of PubMed and MEDLINE, which included all English-language articles published between 2000 and 2024 was completed. Various combinations of free-text and MeSH headings, including “multiligament knee injury” or “MLKI”, “ACL reconstruction”, “concomitant ligament injury”, “return to play”, “athlete” and others, were used to identify pertinent articles. Studies reporting on the epidemiology of MLKI, biomechanical factors, classification, operative techniques, graft selection, tunnel placement, postoperative rehabilitation, and RTP outcomes were retrieved and reviewed. Emphasis was placed on clinical studies, systematic reviews, expert consensus statements, and select biomechanical studies. Publications not written in English, as well as cadaveric-only studies and animal studies were excluded. Title and abstract screening was independently completed by two reviewers, followed by full-text review to determine final inclusion.

Findings and discussion

Epidemiology and mechanisms of injury in high-level athletes

MLKIs are rare and may or may not be associated with a frank knee dislocation (1,2). The most common mechanism of MLKIs is either direct or indirect high energy trauma to the knee, such as in motor vehicle collisions. Labarre et al. (3) retrospectively evaluated 235 athletes with MLKIs and found injury patterns of 43.3% due to motor vehicle accidents, 42.3% to sports-related, and 8.8% due to fall from a low height. While this data is not conclusive, it gives a relative idea of the proportion of sports-related MLKIs.

Sport-specific injuries in high-level athletes have been minimally investigated and evaluated in relation to the biomechanics of the sport. Clifton et al. surveyed knee sprains in youth, high school, and collegiate football players which showed that overall rates increased as competition levels increased. The overall distribution of injury involving primarily the MCL with a 0.43 injury rate per 1,000 athlete-exposures, whereas the ACL involvement rate was 0.15 per 1,000 (4). Overall, football has a higher likelihood of MLKIs, likely due to higher energy mechanisms and effects of direct contact to the knee while tackling. Injury rate ratios also increase as level of competition increases (4,5). One study showed that compared with soccer, skiing had increased odds of isolated ACL injuries [odds ratio (OR) 1.13], but American football had a higher likelihood of MLKI (OR 2.26) than soccer (5). Kompel et al. evaluated knee ligament injuries of Olympic athletes in the 2016 Rio games and identified 113 athletes who received an MRI for a knee injury (6). A total of 43 ligament sprains were identified. ACL/MCL injuries were the most common injury pattern; however, PCL injuries with an associated collateral ligament were more commonly seen than an isolated PCL injury in this Olympic population. This finding highlights the frequency of MLKIs in athletes and demonstrates the need for further studies investigating functional outcomes and return to sport.

Understanding the biomechanical components to injury patterns is important in MLKI management. The 4 major ligaments keep the knee in static stability with the cruciates restraining primarily in the sagittal plane and collaterals as primary restraints in coronal stability with valgus and varus stress. Dynamic stability relies on the ligaments as primary and secondary stabilizers in specific planes, while the quadriceps and hamstrings take over during continuous use in ligamentous failure (7). The cruciates also act in the sagittal plane as part of the kinematic chain, with the gastrocnemius and soleus absorbing ground reaction forces which dissipates strain placed on the ligaments (8). In sports, different maneuvers quickly alter the plane of motion and changes which ligament carries that force burden. Understanding these rapid shifts in biomechanics and force can aid in the identification of MLKI patterns.

ACL/MCL injury patterns

Most MLKI patterns involve injury to the ACL. Of these, ACL/MCL was the most common injury pattern accounting for 75% of knee sprains of 2016 Rio Olympians (6). In cutting sports, such as hockey, the incidence of ACL injury with a collateral involvement is higher (6). In the sagittal plane, the ACL acts as the primary stabilizer with the MCL as secondary, therefore deficiency of one places greater strain on the other (7). Boden et al. (8) used videos to assess differences in landing position in injured versus non injured athletes of various sports, describing maneuvers and body positioning that places greater strain on the ACL. The major theoretical components that increase stress on the ACL are excessive hip flexion, hip abduction, and valgus knee displacement (8). Hip abduction is seen in cutting, jumping and landing maneuvers. Weakness in the hip abductors allows for internal rotation of the knee into the valgus position. The multi planar loading leads to instability in valgus position placing strain on the MCL, medial patellofemoral ligament, and 30% greater strain on the ACL (9). Females have been shown to have decreased hip mobility and a higher propensity to land with restricted hip flexion that is sustained, therefore taking longer to reach neutrality (10). Additionally, females have weaker medial knee compartments and hip abductors which allows for confounded valgus positioning of the knee (10). In sliding maneuvers, the trunk leans laterally, shifting the center of mass placing greater strain in the sagittal plane (11). This trunk lean with the inclusion of external tibial rotation in sliding places a greater strain on the MCL and subsequently ACL, therefore increasing risk of rupture (11).

ACL/LCL or ACL/PLC injury patterns

It is important to note that the similar mechanisms seen in ACL/MCL injury patterns occur with varus shifts conversely placing strain on the LCL and PLC. LCL injuries are extremely rare in isolation, but occur concomitantly in 1–16% of all MLKIs (12). Poploski et al. identified patterns of MLKI involving a variety of injury mechanisms, finding that 20.7% occurred in ACL with medial injury and another 23.2% were ACL with lateral injury (13). The combination of translational forces, external rotation, and varus loading places strain on both the LCL and PLC creating this external rotation instability (14). In cutting movements, the excessive varus stress and external tibial rotation places increased stress on the PLC while also further straining the ACL, increasing rupture risk.

Bicruciate injury patterns

PCL injuries account for about 3% of ligamentous knee injuries, and rarely occur in isolation (6,15). In up to 95% of cases of the 2016 Olympians, PCL injuries were concurrent with another ligamentous injury primarily to the collateral ligaments (6). In these cases, 46% are associated with ACL injuries, 31% in MCL injuries, and 62% in PLC injuries (15). While isolated PCL injuries occur with impact while the knee is in flexion, in combination with ACL, these injuries can occur at all degrees of flexion; most notably in non-contact knee hyperextension during athletic play (16). Hyperextension is associated with high varus torque placing more force on medial compartment compression and lateral distraction (17). This accumulation of forces causes greater stretch of the cruciates and posterolateral ligaments (17).

Classification of MLKIs

Although a football player being tackled represents a lower energy mechanism compared to a motor vehicle collision or a fall from height, it still involves a substantial transfer of energy to the knee. Establishing a classification system for MLKIs is essential for standardizing communication among orthopedic providers. Such a system should be straightforward, reproducible, and facilitate accurate identification of the injured anatomical structures.

The most commonly used classification based on anatomy is described by Schenck for knee dislocations. This system has been extrapolated, potentially erroneously, to include all MLKIs, even those never having sustained a dislocation. The anatomic classification simplifies the anatomy to four defined ligaments: ACL, PCL, MCL and PMC, and LCL and PLC (18). The anatomic system is created such that the higher the number, the greater the injury, or more ligamentous involvement; with “C” and “N” used to denote associated arterial or neural injury, respectively (Table 2) (18). Identification of the ligaments involved includes thorough clinical evaluation with knee stability tests and associated magnetic resonance imaging (MRI). However, Li et al. reported that MRI alone has limited value in classifying MLKIs according to Schenck classification (19).

An adapted, pathoanatomic MLKI classification has been described by Poploski et al. In this system, each ligament included is a grade III tear or partial tear requiring surgery and is denoted as MLK 1–4. In an MLK 1, there is complete tear of a cruciate (denoted by A for ACL or P for PCL) and either a lateral or medial structure component (13). Medial components (denoted by M) include the superficial MCL (sMCL) and/or PMC, while the lateral components (denoted by L) include LCL and/or PLC (13). For example, grade III tears of the ACL and sMCL would be classified as an MLK 1-AM. Additionally, a single cruciate ACL tear with both a medial and a lateral injury can be denoted as MLK 1-AML. An MLK 2 is bicruciate injury without injury to the medial or lateral collaterals (13). MLK 3 is bicruciate injury with an additional medial or lateral collateral, and is denoted as MLK 3-M or MLK 3-L (13). An MLK 4 includes bicruciate with both collaterals injured (13). Similar to the Schenck Classification, “C” and “N” are used to signify arterial or nerve injury, respectively. This classification better describes the different patterns of MLKIs while maintaining the anatomic simplicity of the Schenck classification.

Diagnosis and early assessment in the athlete

Diagnosis of MLKIs in high-level athletes relies on early evaluation at time of injury for life or limb threatening injuries. Although 50% of knee dislocations present spontaneously reduced, immediate reduction should be performed if there is gross dislocation (1,14,18). Additionally, a thorough neurovascular examination is critical with documentation of distal pulses, capillary refill time, and lower limb function (1). In the setting of delayed presentation to clinic, thorough ligamentous exam is critical to identify injuries to structures other than the ACL. Special, or provocative, testing is used to isolate and test the stability of each ligament. MRI is highly sensitive for detecting ACL and PCL injuries (90.7% and 90.4%, respectively) and moderate sensitivity for MCL and LCL injuries (79.1% and 55.6%, respectively) (19). Although specificity of MRI for all ligaments is moderate (19), MRI in conjunction with a careful history and physical examination is best practice to identify ligament injuries.

The treating physician should also consider stress radiographs for assessment of ligamentous laxity and, in certain cases, an examination under anesthesia to identify functionally injured structures. In the setting of a clinical exam with ligamentous laxity, stress radiographs can identify ligamentous injury that is not seen on MRI. LaPrade et al. investigated lateral gapping in cadaveric grade III PLC injuries at 3.4 mm in both standardized 12 Nm and clinician-applied varus stress, which was reproducible, highlighting the value of stress radiographs in conjunction with physical exams (20). In medial compartment valgus stress views, a reproducible 3.2 mm gapping at 20 degrees of flexion was significant to identify a concomitant MCL injury (21). In the case of a 17-year-old female soccer player who presented after a new injury in her first return to practice post-ACL reconstruction, MRI noted an isolated ACL graft failure (Figure 1). She presented with a positive Lachman and a 2+ Pivot shift test but also had significant valgus laxity in full extension and 30 degrees of flexion. Intraoperative valgus stress radiograph demonstrated significant medial compartment widening (Figure 2) indicating a missed MCL injury likely at the time of initial ACL surgery, highlighting the importance of clinical exam and stress radiographs to develop a comprehensive surgical plan to address all abnormal pathology.

Figure 1 MRI imaging of a 17-year-old female soccer player with early failure of ACL graft. MRI imaging showed ACL graft failure and intact MCL, however, clinical evaluation also had significant valgus laxity. (A) Sagittal MRI showing ACL graft failure. (B) Coronal MRI showing intact MCL. ACL, anterior cruciate ligament; MCL, medial collateral ligament; MRI, magnetic resonance imaging.

Figure 2 Radiographs of the same 17-year-old in Figure 1. Intraoperative valgus stress exhibiting widening of the medial compartment.

Early evaluation of neurovascular status is critical when diagnosing MLKIs as this can be limb threatening. 18% of MLKIs have associated vascular injuries with studies reporting incidence in knee dislocations between 1.6–64% (13,14,22). In the setting of knee dislocations, the popliteal artery is most at risk (18). Ng et al. reported that absent pedal pulse has a sensitivity of 0.79 and specificity of 0.91 for vascular compromise (1). Absence of palpable pedal pulse should be evaluated with a pulse doppler radar, and continued absence should undergo immediate surgical intervention. In suspected vascular injury, Ankle-Brachial Index (ABI) should be considered as part of the work-up. An ABI <0.9 is 100% specific, 100% sensitive, and has 100% positive predictive value for vascular injuries (1). In most modern trauma hospitals, computed tomography (CT) angiography is routinely used with or without ABI to assess for any vascular compromise. If there is any concern regarding vascular status, emergent vascular consultation should be obtained (1,14).

Up to 40% of MLKIs are associated with common peroneal nerve (CPN) injury, specifically in knee dislocation with the highest incidence in lateral or posterolateral injuries (1,14). The CPN provides motor function for dorsiflexion of the foot, extension of the great toe, and ankle eversion with palsy causing foot drop (23). Functional recovery in complete CPN palsy is 38% and complete recovery in partial CPN palsy reported as 87% (1). Treatment options include observation with physical therapy and orthotic, neurolysis, nerve grafting, or posterior tibial tendon transfer (1). Limited data has shown up to 75% functional recovery for nerve grafting in lesions <6 cm for all causes of CPN (1). Posterior tibial transfer is generally recommended in complete CPN with the goal of restoring ankle dorsiflexion (1).

Treatment considerations for athletes

Nonoperative vs. operative management

Surgical intervention remains the standard of care for MLKIs in high-performance athletes, as prior systematic reviews consistently demonstrate better functional outcome scores with operative management (1). A recent consensus statement concluded that current evidence generally supports operative management over nonoperative treatment for MLKIs, particularly in patients under 50 years of age, with most studies demonstrating superior functional outcomes and higher rates of return to work or sport following surgical intervention (24). Non-operative management is typically reserved for isolated collateral injuries and consists of functional bracing, progressive loading, and sport-specific neuromuscular training when time constraints or an in-season injury necessitate a temporary delay in surgical intervention (25).

The most common scenario where nonoperative treatment may be utilized is with the ACL/MCL knee injury. The MCL has a rich extra-articular blood supply and thus the ability to heal with nonoperative management. Standard practice involves an observation period of 4–6 weeks with repeat evaluation to determine if the MCL has sufficiently healed. This is important to avoid undue surgery with MCL repair or reconstruction. Similarly, if an ACL-only reconstruction is performed and not all concomitant pathology addressed, the knee is at a higher risk of recurrent laxity and graft compromise. In ACL + MCL injuries, conservative management of the MCL has been widely accepted in low-grade tears, with retrospective review evaluated several studies demonstrating excellent valgus and anterior-posterior stability when the ACL is reconstructed and the MCL allowed to heal non-operatively (26). However, for high-grade injuries or failed conservative treatment, anatomic reconstruction of the medial structures, particularly the posterior oblique ligament (POL), may be warranted to restore stability and minimize residual laxity (26).

Nonoperative management must be approached with caution in athletes, given the risk of chronic instability, secondary cartilage damage, and delayed return to sport if concurrent ligamentous injuries are missed or underestimated (27).

Surgical decision-making in high-performance athletes

In elite athletic populations, surgical decision-making must be highly individualized, balancing the urgency of RTP with the complexity of MLKI reconstruction. Timing of surgery in this specific population can be controversial, and no consensus exists regarding the best timing of surgery, although preference is typically given to early surgery within 6 weeks of injury.

Timing

Timing of reconstruction varies, but typically consists of early, delayed or staged reconstruction. Each of these options has benefits and drawbacks and must be carefully considered based on the individual athlete’s needs and preferences. Repair versus reconstruction is a question that must be addressed, and typically repair is reserved for avulsion fractures and is done within the acute period (27). In a study by McCarthy et al., 60 patients (61 knees) were identified who sustained either an isolated PLC injury or PLC injury with other concomitant ligamentous injury. Forty-three knees underwent reconstruction and 18 knees underwent repair of the PLC, with two failures in each group and similar Lysholm scores at final follow-up. Time from injury to surgery in the repair group was an average of 2.1 weeks and all repair patients were operatively treated within three weeks of injury (28).

Early reconstruction has the benefit of less scar tissue, thus making peroneal nerve neurolysis and identification of anatomical landmarks easier and potentially leading to less damage to surrounding structures (29). Early surgery also allows for repair of injured structures if indicated; however, the authors recommend augmenting any repairs with a reconstruction in the multiple ligament injured knee. A systematic review by Levy et al. identified five studies comparing a cumulative of 80 patients who underwent early versus 50 patients who underwent delayed reconstruction of a MLKI, however ligament distribution injury pattern was not presented in this systematic review (30). They demonstrated overall better clinical outcomes with early reconstruction including improved Lysholm and IKDC scores compared to a delayed reconstruction group (31). However, early surgery (within 3 weeks) is typically associated with higher rates of post-operative stiffness, and patients may require lysis of adhesions or a manipulation under anesthesia more frequently if treated acutely (30).

Delayed reconstruction has traditionally yielded better outcomes in older literature. Delayed reconstruction has the benefit of allowing athletes to work on aggressive range of motion prior to surgery, therefore decreasing their chance of arthrofibrosis post operatively. Another benefit of delayed reconstruction is the potential for some ligamentous and tendinous structures to heal without surgical intervention (30).

Single-stage surgical reconstruction offers several advantages in the management of MLKIs, particularly in athletic populations where early mobilization and return to sport are critical. While the choice between single and staged procedures should be guided by injury pattern, patient-specific factors, and associated comorbidities, expert consensus supports single-stage intervention when feasible (24). Performing all necessary reconstructions in a single operative setting can reduce overall anesthesia exposure, shorten cumulative recovery time, and facilitate earlier initiation of rehabilitation-key factors for optimizing functional recovery in elite athletes (24). This approach aligns with the priorities of sport-related MLKI care, where minimizing time away from competition is essential. Although high-quality comparative data remain limited, proponents of single-stage surgery emphasize its practical and logistical benefits, particularly in cases without complicating factors such as open fractures or extensor mechanism disruption. When anatomical repair is technically feasible and soft tissue conditions allow, single-stage reconstruction provides an efficient, outcome driven strategy that supports early functional gains and streamlined care pathways.

In situations with extensive soft tissue injury or vascular problems and a high potential for arthrofibrosis, like fracture-dislocations, surgeons may perform staged reconstruction to first restore joint stability and range of motion before definitive surgical reconstruction. A staged reconstruction approach might become preferable for some surgeons when resource availability, like time, exists. Staged reconstruction is also appropriate with concomitant injury to the extensor mechanism, which takes precedence and often has a rehabilitation strategy different from the MLKI reconstruction.

Current prospective, randomized controlled trials are underway to address some of these questions including timing of surgical intervention. Treatment decisions should be individualized, carefully considering the athlete’s goals and their tolerance for the associated risks. In general, for the elite athlete, the authors recommend early surgical reconstruction of all injured structures with a focus on post-operative motion and swelling control.

Graft options

Graft selection plays a pivotal role in surgical planning for athletes with MLKIs. There is currently no literature supporting a superior graft; therefore, each case must be considered carefully. Graft selection is typically influenced by the number of ligaments needing reconstruction or augmentation, the availability of graft material, the surgeon’s preference, and the specific surgical technique employed, as some methods necessitate longer grafts or more tissue to address all injured structures (1).

Autografts remain the most used and preferred graft source due to their theoretically lower re-rupture rates and superior rates of incorporation, especially in younger, high-demand individuals (26). However, data supporting autograft use only exists in the isolated ACL reconstruction literature for the young, high-demand athlete and cannot be extrapolated to the multiligament knee literature. There are instances where despite bone-patellar tendon-bone autograft being the “gold standard” it must be avoided, such as following the harvest of a full-thickness quadriceps tendon-bone autograft, where additional harvest from the extensor mechanism could increase the risk of extensor mechanism graft morbidities such as persistent weakness and risk of patellar fracture (32). Many unique cases require a tailored approach, carefully weighing the individual circumstances to select the surgical option that best minimizes donor site morbidity while optimizing overall joint stability for the athlete.

Allografts have gained popularity in multiligament reconstruction and revision cases due to their potential to reduce operative time and minimize donor-site morbidity. Use of at least some allograft for the MLKI reconstruction has become standard; however, their use may be limited by availability of high-quality tissue in some regions, and outcomes in athletic populations remain variable, requiring further investigation (32).

Avoiding tunnel collision

Tunnel convergence remains a significant technical challenge in MLKI reconstructions, particularly in cases involving bicruciate and collateral ligament reconstructions. Convergence between graft tunnels can compromise fixation, jeopardize graft integrity, and ultimately lead to reconstruction failure. Meticulous preoperative planning, precise knowledge of anatomical landmarks, and intentional angulation of drill trajectories are all essential to mitigate this risk. The medial femoral condyle poses particular difficulty, where several tunnels may be required for PCL, sMCL, and POL reconstruction. Similarly, tibial tunnel congestion becomes a concern when both cruciate ligaments and meniscal roots are addressed concurrently.

Cadaveric and 3D modeling studies have outlined effective strategies to avoid convergence. For example, the POL and sMCL tunnels can be oriented anteriorly and proximally in both axial and coronal planes, to minimize overlap with the sMCL and PCL femoral tunnels respectively (33). On the tibial side, aiming the POL tunnel 15 mm medial to Gerdy’s tubercle and angling the sMCL tunnel 30° distally across the tibia can create adequate spacing (Table 3) (33). An example of this adaptation is seen in a 17-year-old female with ACL graft failure and anterior tibial tunnel with cortical blowout 8 months post-operatively, with a missed MCL injury, discussed earlier (Figure 3). Reconstruction required a 2-stage approach; first stage with bone grafting then a second stage revision ACL reconstruction with quadriceps autograft and MCL reconstruction with POL imbrication (Figure 4). When reconstructing the PLC, lateral femoral condyle tunnels for the LCL and popliteus tendon should be angled 35–40° anteriorly to prevent collision with the ACL femoral tunnel (Table 4) (33). If tunnel convergence remains a concern despite these precautions, intraoperative fluoroscopy and guide pin drilling before reaming can be employed to confirm adequate spacing.

Figure 3 X-ray images of a 17-year-old female with a history of ACL reconstruction with LET and meniscus repair from an outside hospital with early failure at 8 months. (A) Lateral X-ray showing anterior position of the tibial tunnel with cortical blowout. (B) AP view of tibial tunnel. ACL, anterior cruciate ligament; AP, anteroposterior; LET, lateral extra-articular tenodesis.

Figure 4 Follow-up imaging 15 months post-op after staged revision with stage one bone grafting and stage two ACL revision reconstruction with quadriceps autograft and MCL reconstruction with POL imbrication. (A) AP view. (B) Lateral view. ACL, anterior cruciate ligament; AP, anteroposterior; MCL, medial collateral ligament; POL, posterior oblique ligament; post-op, post-operation.

In complex reconstructions such as KD-IV injuries (ACL, PCL, MCL/PMC, and PLC), additional strategies include drilling tunnels for medial meniscus root repairs between the cruciate ligament tunnels and the MCL, and sequencing tunnel creation to prioritize spatially demanding tunnels first (Table 3). Using smaller diameter tunnels, suspensory fixation, or cortical buttons may further mitigate risks in small knees. Ultimately, success hinges on surgeon familiarity with knee anatomy, anatomic reconstructions, and intraoperative adaptability to maintain the integrity of all reconstructed structures while avoiding tunnel collision.

Rehabilitation and RTP considerations

There are several considerations involved with an athlete choosing to RTP following a MLKI. Literature regarding RTP is limited in the MLKI. Recently, there is renewed focus on emerging rehabilitation protocols related to timeframe for weight bearing and range of motion exercises, as well as the psychologic factors critical to successful return.

Borque et al. evaluated RTP in 136 elite athletes with MLKIs, demonstrating a RTP rate of 88.2% (34). Upon returning, 85.8% of athletes returned to the same level or higher (34). The length of time prior to RTP differed from unicruciate injuries (approximately 12.4 months) compared to bicruciate injuries (approximately 16 months), although rates of return were comparable (34). When comparing medial and lateral sided MLKIs, although rates of return were similar, lateral sided injuries took longer before returning (34). Ability to return to the same level of play and sport, age at time of injury, and secondary injuries all impact an athlete’s ability to make a full return. The isolated ACL literature has shown us that RTP is positively associated with being an elite athlete, being younger in age, and male (22,35). Although graft selection may impact RTP and reinjury rate in the isolated ACL patient, this has not been elucidated for the MLKI patient (35).

Fine et al. identified 30 athletes (mean age 18.1 years, ranging from high school athletes to recreational adult sports to collegiate and professional athletes) in a retrospective cohort with average follow-up of 7.8 years, all but 2 having an ACL component to their MLKI (36). They found that RTP was achieved by 90% of patients, and 43.3% returned to their preinjury level or higher (36). Important to note, those who stopped playing or returned to a lower preinjury level were more likely high school athletes or recreational athletes, furthering the idea that elite athletes (collegiate or professional) are more likely to return (36). Patients who had played sports at a higher level before injury were more likely to RTS at their preinjury level or higher, while those who played cutting sports were less likely to do so.

MLKI reconstruction failure rates have been reported around 2.9–14.5%; however, data is limited with short follow-up periods (1,34). In retrospective reviews of MLKIs, acute surgery resulted in better range of motion and stability, and 92.2% of 136 elite athletes who underwent surgical intervention for MLKI returned to play faster than those who waited greater than 3 weeks (1,34). There is little consensus on a specific rehabilitation protocol for MLKIs, however multiple protocols have been investigated (Table 5). For example, at the author’s institution, the post-operative rehabilitation protocol for MLKIs encourages early range of motion to prevent stiffness, which is the most commonly reported complication (34). This is done in the setting of PT support, as it is still important to prevent excessive anterior or posterior translation. A brace is utilized and locked at 0 degree extension for two weeks, with progression to full ROM by week 6. Early quadriceps activation is critical. Weight bearing progression is highly recommended as it allows the joint to safely accommodate increasing load, typically beginning at 6 weeks post-operatively (46). Postoperatively, bracing is recommended acutely as it protects the graft by limiting range of motion, but has little support in long-term use in preventing re-injuries (46,47). A PCL-support brace is often used in the setting of PCL reconstruction to allow the ligament to heal with an anteriorly directed force on the tibia. As athletes progress in recovery, closed kinetic chain exercises are safe because they minimize stress on the ACL but allow for strengthening (47). At 3 months patients should be able to begin straight line jogging, dynamic exercises, and single-leg activities with progression to sports specific maneuvers, such as cutting and pivoting, between 5–6 months (47,48).

One notable consideration for patients is evaluating the psychological impact of the injury. Buerba et al. concluded that 40% of elite athletes undergoing ACL reconstruction experienced depression (22). Truong et al. evaluated 77 studies with over 5,500 participants with a knee injury, 84% with an ACL tear, for psychological factors that attributed to recovery and determined one of the greatest barriers was fear as 20–45% of athletes stated it as the dominant reason (49). Post-injury psychosocial factors can also play a major role in athletes’ RTP after suffering a MLKI. Kinesiophobia can lead to suboptimal participation in rehabilitation and prolonged time away from sport (50). Higher anxiety levels, lower self-efficacy and perceived readiness to return are associated with poor functional outcomes and less likelihood of returning to sport after ACL reconstruction and MLKI reconstruction alike (36).

Direct data for MLKI and psychological factors is limited, however, related work can be drawn from. Ardern et al. conducted a scoping review of psychosocial aspects of RTP, and they found that active coping, perceived autonomy, recovery expectation, and reinjury anxiety are all factors that can change throughout the recovery period, and can have an effect on short term outcomes and long term athletic satisfaction (51). Although there are limited data for MLKI specific populations, there is some data from isolated ACL injuries. This work has supported that including psychosocial rehabilitation and an organized mental skills training program can result in improved rehabilitation compliance and RTP. Other barriers include knee and sport confidence, and preservation of independence (50). Success in rehabilitation and RTP is athlete specific; however, especially in the setting of MLKI, extensive social support, goal setting and adaptive protocols can be beneficial (22,49).

Future directions in athlete knee injury management

The management of MLKIs in elite athletes is poised to benefit from several emerging innovations in biologics, surgical technique, and rehabilitation science. Regenerative medicine, including the use of platelet-rich plasma (PRP), mesenchymal stem cells (MSCs), and growth factors, has demonstrated early promise in enhancing graft integration and soft tissue healing—particularly in environments where healing must be accelerated without compromising structural integrity (52). For example, the hemarthrosis resulting from acute ACL injury has been shown to contain a rich mix of proinflammatory and anti-inflammatory cytokines, growth factors, and MSCs (53). However, these MSCs have not yet been utilized in ACL repair or reconstruction. These biologics may eventually support earlier RTP timelines by optimizing the biologic environment for ligament healing and minimizing inflammatory cascades that contribute to fibrosis and arthrofibrosis.

The timing of surgery and the design of rehabilitation protocols remain key areas of ongoing research, with the potential to form treatment strategies and help tailor interventions that best meet the individual needs of athletes. The STaR (Surgical Timing and Rehabilitation) trial, one of the largest prospective studies of MLKIs, is expected to provide critical insights into the optimal timing of ligament reconstruction (early vs. delayed), as well as the ideal progression of weight bearing and ROM (13). Early surgical intervention may benefit from improved tissue quality allowing repair of injured structures, but must be balanced with the risk of arthrofibrosis.

As rehabilitation progresses, secondary interventions such as lysis of adhesions and manipulation under anesthesia may be necessary in athletes experiencing range-of motion deficits. While these procedures can improve functional mobility, they also delay full RTP and should be reserved for refractory cases. In the setting of graft failure or reinjury, revision surgery remains technically demanding, requiring careful tunnel planning, management of hardware, and possible staged reconstruction with bone grafting or osteotomies. Outcomes for revisions in elite athletes, while improving, still lag behind those of primary procedures, underscoring the need for durable and precise primary interventions.

Conclusions

Elite athletes who sustain MLKIs face a complex and potentially career-ending condition which necessitates prompt treatment based on both personalized and evidence supported approaches. Even surgeons and rehabilitation teams face serious challenges when treating these injuries due to the knee’s intricate anatomy alongside diverse injury types, while trying to return athletes to achieve peak performance again. The fundamental treatment approach involves surgical intervention which is customized according to injury pattern and graft availability as well as timing, while evidence grows to support anatomical reconstruction and careful graft selection with attention to tunnel convergence in order to decrease the likelihood of failure. While nonoperative treatments work for select low-grade collateral injuries they prove to be unreliable for athletes with high physical demands because of the potential for residual instability.

Nevertheless, surgery alone is insufficient. Sport-specific rehabilitation programs that address elite athletic demands are essential for achieving optimal recovery. Novel biological treatments and regenerative techniques such as PRP and stem cell therapy demonstrate promise to improve graft recovery while potentially shortening the period before athletes can RTP. The results from studies in this review such as the STaR trial will guide the development of future protocols for surgery timing and rehabilitation sequencing leading the field toward personalized, data-driven decision-making processes. A sustainable comeback to competition that protects joint health over time needs top-notch surgical and rehabilitation practices along with a complete understanding of the athlete’s physical state, mental condition and career path.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editors (Jeremy Burnham, Brian Godshaw and Patrick Cook) for the series “Evaluation and Treatment of ACL Injuries in High Level Athletes: The Continuum of Care” published in Annals of Joint. The article has undergone external peer review.

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://aoj.amegroups.com/article/view/10.21037/aoj-25-28/rc

Peer Review File: Available at https://aoj.amegroups.com/article/view/10.21037/aoj-25-28/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aoj.amegroups.com/article/view/10.21037/aoj-25-28/coif). The series “Evaluation and Treatment of ACL Injuries in High Level Athletes: The Continuum of Care” was commissioned by the editorial office without any funding or sponsorship. D.L.R. received consulting fees from Stryker and Best in Class MD, holds a leadership role in the AOSSM Committee, and has received fellowship funding support from Arthrex and Stryker. None of these relationships is directly related to the content of this narrative review. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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