Multiligament-injured what the general orthopedic surgeon should know

Authors: Michael Hantes, Vasileios Raoulis, Aristeidis Zibis, Nikolaos Metaxiotis, Artemis Hante, Nikolaos Stefanou, Vasileios S Akrivos

Abstract

Multiligament knee injuries (MLKIs) are rare but severe injuries involving bicruciate or collateral ligament disruption, frequently associated with knee dislocation, fractures, and neurovascular compromise. Vascular injury occurs in a mean of approximately 18% of cases and may be present despite palpable pulses; an ankle–brachial index (ABI) < 0.9 demonstrates high sensitivity for arterial injury. Peroneal nerve injury occurs in approximately 10–40% of cases.Early recognition and structured evaluation are critical. Serial vascular examinations, selective CT angiography, and careful neurologic assessment are mandatory. General orthopedic surgeons often make the initial management decisions, and timely diagnosis, stabilization, and referral significantly influence limb salvage and long-term function.The Schenck KD classification remains standard, with recent consensus refinements to the KD V category and proposed modifiers such as ‘–EM’ for extensor mechanism disruption. Associated meniscal, chondral, and rare entities, such as uniplanar coronal tibiofemoral subluxation, require high clinical suspicion.Knee-spanning external fixation is indicated in vascular injury, open or fracture-dislocations, soft-tissue compromise, or persistent instability, with reconstruction commonly performed later at 3–6 weeks. Current evidence shows no clear superiority of early versus delayed reconstruction in functional outcomes, although early surgery increases stiffness risk.Anatomic reconstruction is generally favored over repair for high-grade PLC and MCL injuries due to lower failure and complication rates. At 2 years, patients retain approximately 80–85% of knee function; however, a gradual functional decline over time is observed. Arthrofibrosis (≈10%) remains the most common complication.

Introduction

Multiligament knee injuries (MLKIs) represent a rare (1) but severe spectrum of traumatic knee instability, defined as injuries involving concurrent rupture of the anterior and posterior cruciate ligaments (ACL and PCL) or other combinations of ligamentous injuries, including the medial collateral ligament (MCL), lateral collateral ligament (LCL), and posteromedial and posterolateral corner (PLC) structures (2, 3). Knee dislocation (KD), whether complete or spontaneously reduced, represents the most severe form of MLKI and is defined by complete loss of tibiofemoral articulation at the time of injury. Knee dislocations account for less than 0.02–0.2% of all orthopedic injuries; however, this figure is likely an underestimation due to missed diagnoses, particularly in spontaneously reduced dislocations. As a result, MLKIs should be considered a functional diagnosis based on ligamentous disruption rather than radiographic appearance alone. They occur predominantly in males, most commonly following high-energy trauma, such as motor vehicle collisions, falls from height, and industrial accidents, and less frequently following sporting injuries (4, 5, 6, 7). These injuries are frequently associated with significant soft-tissue damage, fractures, and neurovascular compromise (8). Sports-related mechanisms, especially contact and pivoting sports, remain an important cause in younger, athletic populations. Αn increasing number of low-energy MLKIs have been reported, particularly in obese patients, following simple falls or twisting injuries (9, 10).

General orthopedic surgeons are frequently the first clinicians to evaluate patients with suspected MLKI, particularly in emergency departments, trauma units, and regional hospitals where subspecialty knee or sports surgeons may not be immediately available. Early management decisions made at this stage – including recognition of the injury, appropriate neurovascular assessment, immobilization, imaging, and timely referral – have a profound impact on both limb salvage and long-term functional outcomes. Despite this, the initial assessment and early management of MLKIs remain challenging, and variability in practice persists due to the injury’s rarity and complexity.

This article aims to provide a comprehensive, evidence-based overview of multiligament knee injuries tailored to the needs of the general orthopedic surgeons.

Injury classification

The Schenck (11) classification remains the most used system for categorizing knee dislocations and MLKIs. There are five major injury patterns in knee dislocations, classified as KD I–V, with higher numbers reflecting greater energy trauma.KD I: multiligamentous injury with one cruciate ligament (ACL or PCL) remaining intact.KD II: bicruciate injury with intact collateral ligaments, rare and usually due to extreme hyperextension without varus or valgus force.KD III: most common pattern – tears of both cruciates and one collateral ligament. Subdivided into medial (KD III-M) or lateral (KD III-L) injuries. Classification is based on physical examination, not MRI alone.KD IV: complete disruption of all four major ligaments, usually from high-energy trauma.KD V: knee dislocation with an associated periarticular fracture (fracture-dislocation).

Additional modifiers include ‘C’ for popliteal artery injury and ‘N’ for peripheral nerve injury. Tendon injuries and avulsions are described separately. MPFL injury is common in severe KD III-M and KD IV injuries and is often best identified on MRI (12).

However, recent evidence highlights substantial heterogeneity in how Schenck KD I injuries are reported. Many unicruciate injury patterns classified as KD I do not represent true tibiofemoral dislocations, with confirmed dislocation occurring in <1% of reported cases (13).

Similarly, challenges were observed in defining fracture-dislocations within the KD V category. A recent international modified Delphi consensus study (14) established specific fracture patterns that should be included within Schenck KD V. Consensus-supported KD V injuries include articular distal femur fractures, tibial plateau fractures involving the weight-bearing surface, higher-grade posterolateral tibial plateau compression fractures (Bernholt IIB, IIIA, and IIIB), peripheral rim compression fractures, Gerdy’s tubercle avulsion with weight-bearing involvement, and displaced extensor mechanism fractures (tibial tubercle and patella). In contrast, isolated ligamentous avulsion fractures, proximal fibular fractures, and nondisplaced extensor mechanism fractures were excluded.

Vascular examination

Vascular injury is the most devastating complication of MLKI and requires immediate recognition and treatment. The popliteal artery is particularly susceptible to traction and shear forces during tibiofemoral displacement. Delayed diagnosis can result in irreversible ischemia, limb loss, or death, with amputation rates increasing substantially when revascularization is delayed beyond 8 h (15, 16).

Importantly, the presence of palpable distal pulses does not reliably exclude vascular injury in the setting of knee dislocation. Intimal disruption or partial thrombosis may permit transient distal perfusion before progression to complete arterial occlusion 2–4 days after the injury. Jones et al. (17) reported that 27% of patients with confirmed arterial injury had palpable pulses at initial presentation, underscoring the limitations of clinical examination alone. The mean reported incidence of arterial injury following knee dislocation is approximately 18.4%, with rates as high as 33% (18, 19).

A thorough vascular examination should be performed at initial presentation and repeated serially. This includes palpation of the dorsalis pedis and posterior tibial pulses, comparison with the contralateral limb, assessment of capillary refill, skin temperature, and color, and a complete neurologic examination.

The ankle–brachial index (ABI) is a valuable, noninvasive screening tool in the evaluation of vascular injury following knee dislocation. An ABI < 0.9 is strongly suggestive of arterial compromise and warrants further vascular imaging (20, 21). Several studies have demonstrated that an ABI threshold of 0.9 has a sensitivity of 95–100% for detecting clinically significant popliteal artery injury, with a reported negative predictive value of 99% for major flow-limiting arterial injury (22). Serial ABI measurements are recommended, as vascular compromise may evolve over time despite an initially normal examination.

Selective imaging protocols based on serial normal vascular examinations have been shown to be safe when strictly followed. Kendall et al. (23) demonstrated that a normal and symmetric vascular examination could reliably screen patients for selective arteriography. This approach was further validated by Stannard et al. (24), who developed a prospective protocol relying on repeated examinations over 48 h. However, this strategy requires meticulous adherence, including frequent nursing and physician assessments. Subtle changes – such as pulse asymmetry, livedo reticularis or racemosa, or discrepancies between examiners – must prompt urgent vascular imaging, as delayed recognition has been associated with limb loss.

Role of CT angiography

CT angiography (CTA) has become the imaging modality of choice for evaluating suspected vascular injury in knee dislocations. CTA should be performed urgently in patients withabsent or diminished distal pulses,ABI < 0.9,expanding hematoma or active bleeding,hard signs of vascular injury, orhigh-energy mechanisms with uncertain clinical findings.

Many trauma centers now advocate a low threshold for CTA (25), particularly in high-energy injuries, as patients frequently undergo CT imaging for associated injuries, making concurrent vascular assessment efficient and reliable. CTA has largely replaced routine arteriography due to its rapid acquisition, high sensitivity, and widespread availability (26).

Importantly, vascular imaging should not delay emergent surgical exploration in patients with clear evidence of limb-threatening ischemia. Immediate arterial repair without prior angiography may be lifesaving in these scenarios (15).

Early involvement of vascular surgery is essential when vascular injury is suspected or confirmed. Management decisions – including revascularization, fasciotomy, and timing of ligament reconstruction – require close collaboration among orthopedic, vascular, trauma, and rehabilitation teams. Institutional treatment algorithms are strongly recommended to ensure timely diagnosis and coordinated care (10, 27).

Neurological evaluation in knee dislocation

Neurologic injury occurs in a mean of approximately 19.2% of knee dislocations, with reported rates ranging from 10 to 40%, most commonly involving the common peroneal nerve (18, 28, 29). Peroneal nerve injury is typically traction-related and is associated with lateral-sided ligament injuries, especially LCL and PLC disruption. Although not limb-threatening, these injuries can significantly impair function, contribute to chronic neuropathic pain, and are consistently associated with poorer functional outcomes in patients with multiligament knee injuries (30).

Neurologic assessment should include evaluation of ankle dorsiflexion, toe extension, and sensation over the dorsum of the foot, with careful documentation of even subtle deficits (31). Peskun et al. (32) reported a 31% recovery rate in patients with peroneal nerve palsy following knee dislocation, with KD III-L. Young age was associated with improved nerve recovery.

Management options include observation, neurolysis, nerve grafting, motor nerve transfer, and posterior tibial tendon transfer. Although neurolysis is commonly performed during posterolateral corner surgery to identify and protect the nerve, there is no strong evidence supporting routine neurolysis over observation (33). Outcomes following nerve grafting in the setting of knee dislocation are generally limited. In a series of 14 patients with common peroneal nerve injury associated with knee dislocation, complete recovery occurred in only 21%, while 29% achieved partial but functionally useful motor recovery. The remaining 50% failed to regain meaningful motor or sensory function. Notably, recovery was more favorable in lesions involving less than 6–7 cm of nerve, whereas more extensive injuries were associated with poor functional return (34). Current evidence supports early consideration of posterior tibial tendon transfer in patients with complete common peroneal nerve palsy or persistent motor deficit without meaningful recovery by 3–6 months. A systematic review including 214 common peroneal nerve palsies demonstrated that fewer than 40% of patients with complete palsy regained functional dorsiflexion (Medical Research Council muscle strength ≥ 3/5), whereas recovery after isolated neurologic interventions ranged from 0 to 30%. In contrast, tendon transfer remains the most predictable method for restoring antigravity dorsiflexion and improving gait mechanics in cases of persistent foot drop (33).

Irreducible knee dislocation

Reduction should be performed as soon as possible using slow, gradual longitudinal traction with controlled manipulation of the proximal tibia. However, irreducibility following an attempted closed reduction should immediately raise suspicion for mechanical interposition of soft tissues or bony fragments.

Common causes of irreducible dislocation include the femoral-sided MCL avulsion with intra-articular entrapment,bucket-handle meniscal tear,displaced tibial spine fracture, anddimple sign because of medial capsular interposition.

In these situations, further attempts with forceful closed reduction must be avoided, as they may worsen soft-tissue injury or compromise neurovascular structures. Urgent open reduction is required to restore joint congruity.

The ‘dimple sign’ (Fig. 1) is pathognomonic for irreducible knee dislocation. It presents as visible medial skin puckering over the distal femur and results from buttonholing of the medial femoral condyle through the medial capsule and retinaculum, often with entrapment of the medial collateral ligament or capsule.

Closed reduction in the presence of a dimple sign is typically unsuccessful and should not be attempted. Recognition of these findings mandates a prompt open reduction through a medial approach.

Associated lesions

Associated injuries are common and clinically significant in MLKIs. A systematic review and meta-analysis reported pooled rates of medial meniscal tears of 30.4%, lateral meniscal tears of 27.5%, and cartilage injuries of 27.5% (18).

Recent international Delphi consensus data demonstrate that concomitant extensor mechanism (EM) disruption significantly alters the management of multiligament knee injuries. Experts strongly supported adding an ‘–EM’ modifier to the Schenck classification to reflect its clinical importance. Across KD II and KD III injury patterns, there was a clear consensus to prioritize repair or fixation of the EM at the index surgery and postpone cruciate or collateral ligament reconstruction. This staged approach is favored due to the urgency of restoring the extensor mechanism, concerns regarding arthrofibrosis, and rehabilitation constraints, although high-level comparative outcome data remain limited (35).

A recently described but under-recognized entity in the setting of MLKI is uniplanar coronal tibiofemoral subluxation (UCTFS) (36). In a multicenter retrospective series of 15 cases (2.2% of 680 MLKIs), UCTFS presented as isolated medial or lateral tibial translation on coronal imaging with preserved sagittal alignment. Most cases (80%) involved lateral subluxation, frequently associated with KD III patterns. A mechanical block to reduction was identified in 60% of patients, including medial soft-tissue sleeve involvement (Fig. 2), bucket-handle meniscal tears, patellar dislocation, and displaced tibial spine fractures; in others, collateral ligament laxity or external fixator malposition was implicated. Importantly, UCTFS was diagnosed at variable time points, including delayed and chronic presentations, underscoring the need for serial biplanar radiographic assessment. Management often required staged procedures and external fixation – uniplanar or hinged – to maintain reduction, particularly in chronic or unstable cases. Failure to recognize this entity may result in persistent instability, arthrofibrosis, or degenerative joint changes, highlighting the importance of attention during both acute management and follow-up of MLKIs.

External fixation

Contemporary evidence supports the selective use of knee-spanning external fixation (KSEF) as a temporizing strategy in the acute management of KDs and MLKIs. Indications most consistently include vascular injury (to protect arterial repair) (Fig. 3), open dislocation, fracture-dislocation, severe soft-tissue compromise, and persistent instability after reduction, as well as select cases of morbid obesity or polytrauma (12). Modern staged protocols typically employ immediate KSEF placement, followed by delayed definitive ligament reconstruction once soft-tissue swelling has resolved – most commonly at 3–6 weeks post-injury, with many centers favoring reconstruction around 4–6 weeks to optimize soft-tissue healing and reduce stiffness risk. This interval allows recovery of the soft-tissue envelope, monitoring of vascular status, and surgical planning, while maintaining joint alignment. Although complications such as arthrofibrosis, infection, and heterotopic ossification have been reported, current evidence suggests these risks are strongly influenced by injury severity and patient factors rather than fixation alone (37).

Timing of surgical intervention

The optimal timing of surgical management for MLKIs remains controversial. Three principal strategies are acute, staged, and delayed intervention. Acute surgery is typically defined as reconstruction or repair performed within three weeks of injury. This interval is considered critical because soft-tissue planes remain identifiable, ligamentous structures are not significantly retracted, and primary repair may still be technically feasible. Proponents of acute intervention argue that early restoration of stability may better preserve knee kinematics and potentially reduce secondary meniscal or chondral injury. However, early surgery has been consistently associated with an increased risk of arthrofibrosis and postoperative stiffness. If arthroscopic reconstruction is performed acutely, some authors recommend delaying 1–2 weeks to allow capsular healing and reduce fluid extravasation risk (38).

Staged reconstruction involves early repair or reconstruction of extra-articular structures (medial and lateral complexes), followed by delayed cruciate ligament reconstruction once range of motion has recovered – typically at 6–8 weeks. Delayed reconstruction is defined as surgery performed more than three weeks after injury. Delayed surgery may facilitate improved preoperative range of motion and reduce stiffness risk (38).

The optimal timing of surgical management for MLKIs remains controversial. A large systematic review and meta-analysis including 14 studies and 1,172 MLKI patients found no significant differences in reoperation rates, complications, stiffness, range of motion deficits, muscle strength, instrumented laxity, or overall functional outcomes between early and delayed surgery, despite early intervention being associated with fewer meniscal and chondral injuries in some studies (39).

Similarly, a comprehensive systematic review of 31 studies encompassing 2,594 MLKIs reported comparable Lysholm, IKDC (International Knee Documentation Committee), and Tegner scores between acute and delayed surgical groups at final follow-up, with no clear evidence favoring either strategy (40). Subgroup analyses – including isolated injuries and polytrauma cases – also failed to demonstrate consistent superiority of early or delayed reconstruction.

However, early surgical intervention (<3 weeks) has been associated with more than double the odds of postoperative stiffness compared with delayed surgery (≥3 weeks; OR 2.18) (41). Conversely, early intervention may reduce the incidence of secondary meniscal and chondral injuries (39). Jiang et al. (42) reported that staged reconstruction has demonstrated favorable outcomes in Schenck KD III injury patterns.

Absolute indications for acute surgical intervention

Certain conditions require immediate operative management. These include the vascular injury requiring repair,tibial-sided MCL avulsion (Stener-type lesion or wave sign) (Figs 4 and 5),irreducible knee dislocation or presence of a dimple sign,intra-articular entrapment of the MCL or other soft tissues, andpersistent gross instability after reduction, preventing safe immobilization.

In these scenarios, delayed treatment is inappropriate. Urgent open reduction and repair of entrapped or avulsed structures should be performed, followed by staged reconstruction of the remaining ligament injuries (42, 65).

Surgical repair versus reconstruction

Posterolateral corner

For acute grade III PLC injuries, contemporary evidence favors anatomic reconstruction over primary repair. A recent systematic review including 12 studies and 288 patients treated within 4 weeks of injury demonstrated an overall surgical failure rate of 12.4%. Importantly, failure rates were significantly higher following primary repair (21.9%) compared with reconstruction (7.1%) (43).

These findings are consistent with the systematic review by Geeslin et al. (44), which evaluated 8 studies comprising 134 patients with acute grade III PLC injuries and reported an overall failure rate of 19%. Notably, repair of the fibular collateral ligament and popliteus complex – often combined with staged cruciate reconstruction – was associated with a markedly higher failure rate of 38%, whereas hybrid or anatomic reconstruction techniques demonstrated failure rates closer to 9%.

Further support for reconstruction comes from the systematic review by Moulton et al. (45), examining chronic grade III PLC injuries. Across 15 studies and 456 patients, all of whom underwent reconstruction, the reported objective success rate was 90%, with a failure rate of 10%. Although techniques varied (including fibular slings, capsular shifts, and anatomic fibular and tibial tunnel reconstructions), outcomes consistently favored reconstructive strategies for restoring varus and rotational stability.

Medial collateral ligament and posteromedial corner

The posteromedial corner (PMC) comprises the superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL), with contributions from the semimembranosus expansions and posteromedial capsule. The sMCL is the primary valgus stabilizer of the knee, inserting proximally near the medial epicondyle and distally along the proximal and distal medial tibia. The dMCL provides meniscocapsular support (46).

The POL is the key posteromedial stabilizer and is frequently injured in anteromedial rotatory instability. Biomechanically, it resists internal tibial rotation and contributes to valgus stability in extension (47). Several techniques have been described to repair or reconstruct the POL, but there is no evidence to show that one technique is superior to the other (38, 48).

Isolated MCL injuries can frequently be managed nonoperatively in a hinged knee brace, although persistent valgus laxity on examination under anesthesia in the setting of MLKI warrants surgical intervention. A systematic review by Kovachevich et al. (49) demonstrated satisfactory outcomes with both MCL repair and reconstruction in MLKIs, with tear location and tissue quality serving as key determinants of surgical approach. Midsubstance and femoral-sided tears are less amenable to primary repair and often require augmentation or reconstruction.

In combined ACL and MCL injuries, Shelbourne and Porter (50) reported that nonoperative management of the MCL combined with ACL reconstruction resulted in excellent stability and good-to-excellent functional outcomes at a mean follow-up of 3.1 years. In a randomized controlled trial, Halinen et al. (51) compared operative versus nonoperative management of grade III MCL injuries in the setting of early ACL reconstruction and found no significant differences in subjective or objective clinical outcomes between groups. While medial laxity measurements were slightly greater in the nonoperative cohort, this difference did not translate into inferior functional scores or increased graft failure at follow-up.

In MLKIs involving high-grade MCL disruption, reconstruction has demonstrated superior structural outcomes compared with repair. A recent systematic review including 30 studies (458 repairs and 590 reconstructions) found that MCL reconstruction was associated with significantly lower rates of arthrofibrosis (5.4 vs 11.6%) and lower overall failure rates (2.9 vs 5.7%) compared with repair. Importantly, in cases involving concomitant ACL injury, ACL graft failure rates were significantly lower when MCL reconstruction was performed (0.2 vs 2.3%) (52).

Despite these differences in complication and failure rates, functional outcomes – including Lysholm, subjective IKDC, and Tegner scores, and stress radiographs – were comparable between repair and reconstruction techniques. These findings suggest that while both approaches can yield satisfactory patient-reported outcomes, reconstruction may provide improved mechanical stability and reduced postoperative complications, particularly in high-grade or combined ligament injuries (52).

Graft choice and technical considerations

Graft selection in multiligament knee reconstruction is complex and depends on the number of ligaments involved, graft availability, surgical technique, operative time, and surgeon preference. Autograft, allograft, and synthetic graft options are all viable, each with distinct advantages and limitations.

Autograft

Common autograft options include hamstring tendon (gracilis and semitendinosus), bone–patellar tendon–bone (BPTB), and quadriceps tendon (QT) grafts. Hamstring grafts are suitable for ACL, PCL, PLC, PMC, and sMCL reconstructions. BPTB and QT grafts are suitable for ACL and PCL, provide bone-to-bone healing, but carry risks of anterior knee pain, extensor mechanism morbidity, and increased operative time due to graft harvest (38).

Allograft

Allografts – including Achilles tendon, tibialis anterior, and BPTB graft – avoid donor-site morbidity and reduce operative time, which is particularly advantageous in complex multiligament reconstructions requiring multiple grafts. Achilles tendon allograft is commonly used for ACL, PCL, and PLC reconstructions, allowing bone-to-bone fixation on one side when a calcaneal bone block is included. Tibialis anterior allograft is frequently used for ACL, PCL, and PLC. BPTB allograft is primarily utilized for ACL and PCL reconstructions when bone-to-bone healing is preferred. Limitations of allograft use include cost, availability, and the theoretical risk of disease transmission (38).

Synthetic grafts

Synthetic grafts, such as the ligament augmentation and reconstruction system (LARS), may be used in ACL, PCL, PLC, PMC, and superficial MCL reconstructions. They eliminate donor-site morbidity and reduce operative time. Mid-term studies of acute repair and augmentation have demonstrated satisfactory outcomes for the ACL and collateral structures; however, persistent posterior laxity has been observed in some PCL reconstructions (53). Revision series following failed LARS ACL reconstruction have reported a high incidence of synovitis and chondral degeneration at the time of revision (54). Although causality cannot be established, concerns regarding long-term biological response and durability remain, and high-level comparative data in MLKIs are limited.

In PLC reconstruction, both autograft and allograft tissues demonstrate comparable graft failure rates and objective stability outcomes. A systematic review and meta-analysis including 22 studies (33 cohorts; 280 autografts and 336 allografts) found no significant difference in graft failure rates (0.44 vs 0.41, respectively) or postoperative varus laxity between graft types. Patient age and follow-up duration were also similar between groups. Although autografts were associated with slightly higher postoperative Lysholm scores (89.6 vs 85.5), there were no significant differences in IKDC scores, suggesting equivalent functional outcomes (55).

Supporting the viability of allograft tissue, a separate PRISMA-guided systematic review of 19 studies (547 LCL or PLC reconstructions) demonstrated significant improvements in lateral stability (mean lateral opening 6.21–1.88 mm) and patient-reported outcomes (Lysholm: 53.4–85.7; IKDC: 44.0–74.8). However, the reported failure rate for LCL or PLC reconstructions using allografts was 11.1%, with a complication rate of 19.8% (56).

For combined single-stage ACL–PCL reconstructions, substantial variability exists regarding graft tensioning protocols, fixation sequence, and knee flexion angle at fixation. A systematic review of 19 clinical studies demonstrated that the PCL is most commonly tensioned and fixed prior to the ACL (17 of 19 studies). In the majority of reports, the PCL was fixed at 70–90° of knee flexion, whereas ACL fixation occurred at highly variable angles ranging from full extension to 70° of flexion. Notably, only a minority of studies described the specific methods or forces used for graft tensioning, reflecting inconsistent reporting standards (57).

Despite these technical differences, patient-reported and objective outcomes were similar across fixation strategies, and no specific graft tensioning sequence or fixation angle has demonstrated clear clinical superiority.

Mechanism of injury and prognosis

Patients sustaining MLKIs via low-energy mechanisms demonstrate higher postoperative activity levels, as reflected by significantly improved Tegner scores compared with high-energy injuries (5.0 vs 3.9). However, no significant differences have been observed in Lysholm scores (78.6 vs 78.0), IKDC scores (69.0 vs 68.4), or graft failure rates (2.0 vs 3.5%) between low- and high-energy injury groups at a minimum 2-year follow-up (58).

Patients who suffered an MLKI can expect to retain around 80–85% of knee function at 2 years. PCL-based injury patterns are consistently associated with inferior outcomes. Meta-analysis demonstrates significantly lower Lysholm and IKDC scores in MLKIs involving the PCL compared with non-PCL-based injuries (59, 60).

Long-term outcomes following MLKI reconstruction demonstrate a gradual but measurable decline over time. A large systematic review and meta-analysis including 3,571 patients across 79 studies reported mean 2-year postoperative scores of 86.1 for Lysholm and 81.4 for IKDC (59). However, a statistically significant yearly decline was observed in both Lysholm (−0.80 points per year) and IKDC scores (−1.99 points per year), indicating progressive functional deterioration beyond the early postoperative period.

Consistent with these findings, long-term single-center data evaluating a delayed reconstruction strategy (mean follow-up 105 months) demonstrated sustained functional outcomes, with mean IKDC 82.1 and Lysholm 90.6, and satisfactory objective stability (KT-2000 difference 2.0 mm). Although radiographic osteoarthritic progression was observed, overall knee function remained good, with age and duration of follow-up negatively influencing clinical scores (61).

Return to sport and work

Rates of return to sport (RTS) and return to work (RTW) following MLKI reconstruction remain highly variable. An updated systematic review including studies published after 2018 reported RTS at any level ranging from 41.2 to 100%, while return to preinjury level ranged from 5.9 to 100%, with substantial heterogeneity (I^2^ up to 91%). Time to RTS typically ranged from 6.7 to 24.9 months, reflecting the prolonged rehabilitation required after complex multiligament reconstruction.

Similarly, RTW rates ranged from 41 to 100% at any capacity and 39.3–100% at preinjury occupational level, with return occurring between 2.4 and 24.8 months postoperatively. Lower RTW rates were observed in patients sustaining multitrauma dislocations, with high-energy mechanisms, and employed in sedentary occupations (62). Additionally, RTS rates were higher after reconstruction (100%) compared with repair (94%), although this difference did not reach statistical significance (43).

Complications

Despite improved stability outcomes with reconstruction, postoperative complications remain common following MLKI surgery. Arthrofibrosis is the most frequently reported complication, with rates ranging from 8 to 20%, and often requiring manipulation under anesthesia. A recent meta-analysis including 4,159 patients reported a pooled postoperative stiffness rate of 9.8% (95% CI 7–13%), confirming that loss of motion remains a substantial concern after MLKI reconstruction. Importantly, injuries involving three or more ligaments were associated with a significantly higher risk of postoperative stiffness compared with two-ligament injuries (OR 0.45 for two-ligament vs ≥three-ligament injuries). Early surgical intervention has also been identified as a significant risk factor for postoperative stiffness (41). Infection rates remain relatively low at approximately 1–2% (63).

In acute grade III PLC injuries, revision reconstruction has been reported in 3.8% of cases, with overall failure rates significantly lower following reconstruction (7.1%) compared with repair (21.9%) (43). A large systematic review of 60 studies comprising 1,747 PLC reconstructions and repairs demonstrated a low intraoperative complication rate of 0.34%, yet an overall postoperative complication rate of approximately 20%, with structural failure occurring in 9.4% of cases (63).

Rehabilitation

Rehabilitation following surgical treatment of MLKI remains heterogeneous, with limited high-quality evidence to support a single standardized protocol. Expert consensus suggests that a period of restricted weight-bearing in a hinged knee brace for approximately 4–6 weeks is reasonable, although this recommendation is based largely on low-level evidence and clinical experience. Progressive weight-bearing is typically introduced thereafter, with emphasis on controlled active motion and avoidance of aggressive passive stretching to reduce the risk of arthrofibrosis (64). Systematic review data indicate that early mobilization after acute MLKI surgery is associated with improved range of motion and stability compared with prolonged immobilization (65). In the setting of PCL reconstruction, early rehabilitation incorporating daily prone range-of-motion exercises (0–90°) within the first week and immediate quadriceps activation is favored over extended immobilization, as it appears to facilitate recovery without compromising stability (64).

Conclusion

Multiligament knee injuries require early recognition and a structured, protocol-driven approach. Based on the current evidence, the following principles are Perform mandatory vascular assessment with serial examinations and ABI in all cases; perform urgent CTA for ABI < 0.9 or abnormal findings, without delaying revascularization in limb-threatening ischemia.Perform thorough neurologic evaluation, particularly for common peroneal nerve injury, with early consideration of tendon transfer if recovery is unlikely.Selectively use external fixation in vascular injury, open or fracture-dislocations, severe soft-tissue compromise, or persistent instability.Prefer reconstruction over repair in high-grade PLC and MCL injuries within MLKIs, given lower failure rates.Individualize surgical timing, balancing soft-tissue condition and stiffness risk, as evidence does not clearly favor early or delayed intervention.Implement structured rehabilitation with early controlled motion to reduce arthrofibrosis.

ICMJE Statement of Interest

The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the work reported.

Funding Statement

This work did not receive any specific grant from any funding agency in the public, commercial, or not-for-profit sector.

Author contribution statement

VSA conducted the literature search, performed the review and synthesis of the relevant publications, and drafted the initial manuscript. VR and AZ contributed to the literature evaluation and interpretation of findings, assisted in drafting sections of the manuscript, and critically revised the final version. NM and AH assisted in the literature search and selection of relevant articles and contributed to manuscript editing. NS contributed to the organization and structuring of the review, preparation of tables and figures, and manuscript revision. MH contributed to the conception and design of the review, supervised the study, critically revised the manuscript for important intellectual content, and approved the final version for submission.