Abstract
Background:
Multiligament knee injuries (MLKIs) are complex and challenging, with significant long-term consequences. While previous studies have examined chondral injuries in MLKI over time, there are limited data regarding their development during the interval between injury and surgery.
Hypothesis:
MLKIs with increased time interval between injury and surgery will be associated with an increased incidence of chondral injuries.
Study Design:
Case-control study; Level of evidence, 3.
Methods:
This retrospective review utilized a multisurgeon database, including patients with MLKI treated from April 2008 to October 2022. Inclusion criteria were MLKI requiring surgical intervention, available operative reports, and documented date of injury in the electronic medical record. MLKIs were categorized by time interval from injury to surgery (acute, 0-90 days; delayed, 91-365 days; late, >365 days). The location and pattern of meniscal and chondral injuries were evaluated accordingly. Compartment injury patterns were also analyzed based on cruciate ligament injury pattern.
Results:
A total of 206 patients were included (acute, n = 138; delayed, n = 54; late, n = 14). The delayed and late groups had significantly higher mean numbers of chondral surface injury (out of 6 total surfaces evaluated) compared with the acute group (delayed, 1.79; late, 1.52; acute, 0.70; P = .002). Trochlear cartilage injuries occurred significantly more frequently in the delayed (28%) compared with the acute group (9%; P = .003). Similarly, patellar cartilage injuries were more common in the delayed (30%) compared with acute patients (12%; P = .02). Medial femoral condylar chondral injuries were significantly increased in the delayed (30%) and late (50%) groups compared with acute (15%; P = .002). Medial tibial plateau cartilage injuries followed the same pattern (acute, 13%; delayed, 30%; late, 43%; P = .002). Patients with bicruciate MLKIs undergoing surgery after 90 days showed significantly higher trochlear (31% vs 8%; P = .04) and patellar cartilage injury rates (35% vs 11%; P = .03). ACL-based MLKIs operated beyond 90 days had increased rates of trochlear (22% vs 8%; P = .03), medial femoral condylar (30% vs 13%; P = .02), and medial tibial plateau (27% vs 11%; P = .03) cartilage injury. PCL-based MLKI patients undergoing delayed surgery (>90 days) also had significantly higher medial femoral condylar (71% vs 8%; P = .004) and medial tibial plateau (71% vs 8%; P = .01) cartilage injury rates. Meniscal injury rates did not differ significantly across time groups.
Conclusion:
Patients who underwent delayed surgery for their MLKI injuries had more medial and patellofemoral cartilage injuries at the time of surgery than those treated within 30 days of injury.
Multiligament knee injuries (MLKIs) represent a severe and multifaceted challenge in orthopaedic trauma, characterized by the involvement of ≥2 major knee ligaments. These injuries most commonly affect the anterior cruciate ligament (ACL) and the medial collateral ligament 15 but also may include the posterior cruciate ligament (PCL) and lateral collateral ligament, often resulting in extensive damage to both ligamentous and nonligamentous structures. The mechanisms of injury are varied, ranging from high-energy trauma—such as motor vehicle accidents and falls from significant heights—to low- and ultra–low energy events such as sports-related incidents and ground-level falls, respectively. 20 While MLKIs are relatively uncommon, 30 they are disproportionately associated with high morbidity due to their complexity and the significant functional impairments they can cause.
MLKIs present significant treatment challenges because of their effect on patient mobility and quality of life, as they are frequently accompanied by damage to other knee structures including cartilage, menisci, nerves, and blood vessels. These concomitant injuries are particularly evident in cases involving concurrent polytraumatic injuries. 37 Furthermore, the complexity of these injuries is compounded by their wide variability ranging from isolated ligamentous injuries with no additional damage, to severe, multisystem traumas involving highly morbid musculoskeletal and nonorthopaedic injuries.1,3,9,34 This variability in injury presentation is paralleled by an equally broad spectrum of management strategies that span from conservative options such as limb immobilization to acute surgical fixation of damaged ligaments.4,7,12,20,27,28,34 Nonligamentous injuries often play a critical role in determining the long-term functional outcomes for patients.8,10,26,34 Specifically, damage to the articular cartilage and meniscus has been shown to be associated with worse outcomes in patients with MLKI at midterm follow-up of 6 years. 17 ACL- and PCL-deficient knees have both been associated with increased rates of chondral injury over time.25,35 However, limited data are available to differentiate these findings in MLKIs or bicruciate injuries. 18
Despite the existing body of research, there is still a significant gap in understanding of the critical time frames during which the presence of chondral and meniscal injuries notably increases. The objective of this study was to characterize the patterns of meniscal and chondral pathology in a large cohort of surgically managed MLKIs, stratified by time intervals from injury to surgery, and make comparisons between meniscal and cartilaginous injury pertinent to cruciate injury status in MLKI. Clinically, understanding how surgical timing affects cartilaginous injury in MLKI to better identify an optimal intervention window may guide treatment decisions, reduce cartilage damage, and ultimately improve patient outcomes. We hypothesize that MLKIs with delayed and late intervals between injury and surgery will be associated with an increased incidence of chondral injuries.
Methods
Following institutional review board approval, all patients surgically treated with ≥2 ligamentous reconstructions/repairs for MLKI at a single tertiary academic medical center between April 2008 and October 2022 were retrospectively reviewed. Inclusion criteria consisted of (1) patients diagnosed with MLKI by an attending orthopaedic surgeon, with ≥2 ligaments surgically treated; (2) availability of preoperative clinical notes; (3) documented date of injury; and (4) availability of operative reports. Exclusion criteria consisted of revision MLKI surgery (n = 3) and patients treated nonoperatively as a result of patient preference (n = 1). Patients who underwent staged surgical treatment were categorized into their respective time group based on the first operation date. MLKIs were identified by reviewing magnetic resonance imaging and confirmed with intraoperative reports showing that ≥2 of the ligaments were surgically treated through repair or reconstruction. Intraoperative reports were reviewed by a single independent researcher (C.D.R.H.) for documented evidence of ligamentous, cartilaginous, and meniscal injuries. Chondral and meniscal injuries were identified arthroscopically by the attending surgeon. Chondral injuries were included if they met criteria for Outerbridge classification 31 of the patellar, trochlear, medial femoral condylar, lateral femoral condylar, medial tibial plateau, or lateral tibial plateau surface. Meniscal injuries were identified based on arthroscopic evaluation and defined as the presence of a tear requiring surgical intervention, including repair, partial meniscectomy, or debridement. Demographic variables such as patient age, sex, and body mass index (BMI) were collected from the patient chart using an electronic medical record (Epic; Epic Systems Corporation). All clinical data were compiled and maintained in a longitudinal REDCap (Research Electronic Data Capture; Vanderbilt University) database.
Patients with an MLKI were categorized by the interval of time between the injury date and the surgical fixation. Acute intervention was defined as those undergoing surgery 0 to 90 days from the inciting injury, delayed intervention was between 91 and 365 days after inciting injury, and late was >365 days after the event causing injury, in accordance with previous research. 19 Ligamentous injury pattern was categorized based on the cruciate injury pattern: ACL-based (ACL-B), PCL-based (PCL-B), and bicruciate.
Statistical Analysis
Data were exported from the REDCap database and imported into SPSS Version 27 statistical software (IBM Corp). Chi-square analysis was used to evaluate the relationship between chondral injuries and time between the acute and delayed intervention groups and the cruciate injury patterns. Categorical comparisons involving the late group were evaluated using a Fisher exact test because of low enrollment. Analysis of variance was used to compare the mean age across the 3 groups and the mean number of chondral surface injuries identified. Independent t tests were used to compare the total chondral injury surfaces between each group. To preserve statistical power and avoid unreliable subgroup comparisons, surgical timing in the cruciate injury pattern analysis was dichotomized as ≤90 days versus >90 days, as further stratification resulted in insufficient sample sizes. Statistical significance was set at P < .05 and a post hoc power analysis indicated a power level of 0.80.
Results
A total of 206 patients with MLKI were included in the study with 138 (67%) patients in the acute group, 54 (26%) patients in the delayed group, and 14 (7%) patients in the late group. A total of 21 patients (10%) were treated in staged operations. Patients were all treated by 1 of 4 surgeons (J.J.E., P.G., S.K.A., T.G.M.) at the same institution. The mean (±SD) age at the time of surgery was 27.1 ± 13.1 years (range, 13-61 years) in the acute group, 30.3 ± 12.4 years (range, 15-58 years) in the delayed group, and 31.4 ± 14.3 years (range, 17–62 years) in the late group (P = .20). The mean (±SD) BMI was 27.5 ± 7.4 kg/m2 in the acute group, 30.5 ± 9.0 kg/m2 in the delayed group, and 29.2 ± 6.1 kg/m2 in the late group (P = .05). Male patients comprised 70% (n = 96) of the acute group, 69% (n = 37) of the delayed group, and 71% (n = 10) of the late group (P = .98) (Table 1). The mean (±SD) time from injury to surgery was 42 ± 27 days (range, 1-91 days) for the acute group, 160 ± 75 days (range, 92-365 days) for the delayed group, and 699 ± 438 days (range, 373-1890 days) for the late group (Table 2).
Demographics of Multiligament Knee Injured Patients Stratified by Time a
Age and BMI variables reported as mean ± SD or n (%). Analysis of variance was used to compare continuous variables (age and BMI) across the time groups. Categorical (sex) was compared using chi-square analysis. No significance was detected across the groups using a statistical significance threshold of P < .05. BMI, body mass index.
Chondral Injuries of MLKIs Treated at Times: Early, Delayed, and Late a
Data are presented as n (%) unless otherwise indicated. Bold values indicate statistical significance. Chi-square analysis was used for categorical comparisons and Fisher exact test was used for categorical comparisons in analyses where expected cell counts were <5.
Patellofemoral cartilage injuries were analyzed by combining the delayed and late groups, as the late group did not meet the minimum threshold of 4 cases required for a reliable chi-square analysis.
One-way analysis of variance test.
Of the 134 knees identified as having an intraoperatively reported intra-articular pathology, 34% (46/134) were chondral injuries, 46% (61/134) were meniscal injuries, and 20% (27/134) were both. The mean number of chondral surfaces injured per patient (out of 6 possible surfaces) was significantly higher in the delayed (1.79 ± 2.3 surfaces) and late (1.52 ± 2.0 surfaces) groups compared with the acute group (0.70 ± 1.5 surfaces) (P = .002) (Table 2, Figure 1). Differences in injuries based on time categories are displayed in Table 3.
Rate of meniscal and chondral injuries categorized and assessed by time intervals: early (0-90 days), delayed (91-365 days), and late (>365 days). *Trochlear and patellar cartilage injuries with late and delayed intervention were combined for statistical analyses. **Significant difference detected at the P < .05 level of significance. LFC, lateral femoral condyle; LTP, lateral tibial plateau; MTP, medial tibial plateau.
P Values for Comparisons of Chondral and Meniscal Injuries Grouped by Time Categories a
LFC, lateral femoral condyle; LTP, lateral tibial plateau; MFC, medial femoral condyle; MTP, medial tibial plateau. Bold values refer to those of statistical significance. Dashes indicate null values, as these tests were not performed.
Early (0-90 days); delayed (>90-365 days); late (365+ days). Fisher’s exact test to determine the significance of delayed vs late trochlear and early vs late patellar groups. Independent t test of means used to detect differences in total chondral injury surfaces.
Patellofemoral Compartment
As a result of insufficient numbers of patellofemoral compartment chondral injuries in the late group to complete chi-square analyses, these were combined for comparison analyses. Trochlear cartilage injuries were observed in 9% (n = 12) of the acute group and 25% (n = 17) of the delayed + late (n = 68) group (P = .003) (Table 2). Patellar cartilage injuries occurred in 12% (n = 17) of the acute group and 26% (n = 18) in the delayed + late group (Table 2) (P = .02). The lower percentage of patellofemoral cartilage injuries in the late group may be attributed to the small sample size, which limited the ability to detect consistent patterns and may underestimate the true incidence of chondral damage in this cohort.
Medial Compartment
Medial meniscal tears were present in 27% (n = 37) in the acute group, 30% (n = 16) in the delayed group, and 50% (n = 7) in the late group (P = .19). Medial femoral condylar cartilage injuries were identified in 15% (n = 21) in the acute group, 30% (n = 16) in the delayed group, and 50% (n = 7) in the late group, demonstrating a significant increase in injuries in the delayed and late groups compared with the acute group (P = .002) (Table 2). Medial tibial plateau cartilage injuries occurred in 13% (n = 18) in the acute group, 30% (n = 16) in the delayed group, and 43% (n = 6) in the late group, with a significant difference between groups (P = .002) (Table 2).
Lateral Compartment
Lateral meniscal tears were reported in 33% (n = 46) in the acute group, 26% (n = 14) in the delayed group, and 36% (n = 5) in the late group (P = .44), showing no significant difference between groups. Lateral femoral condylar cartilage injuries occurred in 10% (n = 14) in the acute group, 17% (n = 9) in the delayed group, and 29% (n = 4) in the late group (P = .10) (Table 2). Lateral tibial plateau cartilage injuries were noted in 10% (n = 14) in the acute group, 19% (n = 10) in the delayed group, and 29% (n = 4) in the late group (P = .08) (Table 2).
Cruciate Injury Pattern Analysis
All patients were categorized into 3 MLKI subgroups: bicruciate (n = 62; 30%), ACL-B (n = 125; 61%), and PCL-B (19; 9%). These groups were further stratified based on the timing of surgery, either within 90 days or beyond 90 days from injury. Demographic data were similar across the subgroups (Table 4). Patients with bicruciate MLKIs who underwent surgery after 90 days demonstrated significantly higher rates of trochlear cartilage injury compared with those operated on within 90 days (31% vs 8%; P = .04), as well as increased patellar cartilage injury (35% vs 11%; P = .03) (Table 4). A similar finding was observed in patients with ACL-B MLKIs, where delayed surgery beyond 90 days was associated with a higher incidence of trochlear cartilage injury (22% vs 8%; P = .03). In addition, ACL-B patients who underwent delayed surgery had higher rates of medial femoral condylar chondral injury (30% vs 13%; P = .02) and medial tibial plateau chondral injury (27% vs 11%; P = .03) compared with those operated on within 90 days. The same was true for PCL-B patients with delayed surgery, who demonstrated higher medial femoral condylar (71% vs 8%; P = .004) and medial tibial plateau (71% vs 8%; P = .01) injury rates as compared with acute surgery. The total number of chondral surfaces involved was significantly greater in patients undergoing surgery after 90 days across all subgroups. There were no differences in lateral compartment injury rates across any of the groups (Table 4).
Comparison of Chondral Injuries of Bicruciate Versus Nonbicruciate MLKIs Treated At >90 or <90 Days a
Data are presented as n (%) unless otherwise indicated. Chi-square analysis was used for categorical comparisons, independent t tests were used for continuous variables, and Fisher exact test was used for categorical comparisons in analyses where expected cell counts were <5. ACL, anterior cruciate ligament; MLKI, multiligament knee injury; PCL, posterior cruciate ligament. Bold values indicate statistical significance.
Discussion
The findings of this study demonstrate an association between greater time intervals from injury to surgery and increased rates of articular cartilage lesions. Specifically, the significant amount of cartilage damage of the patellofemoral and medial compartments increased between the acute (0-90 days) and delayed (91-365 days) periods after the initial injury with no significant changes in chondral injuries observed between the delayed and late (>365 days) periods. Furthermore, there was a significant increase in lateral compartment chondral damage occurring between the acute and late groups, but not between acute and delayed periods. Additionally, the rates of patellofemoral chondral injury were greater in the bicruciate and ACL-B groups, while medial compartment chondral injuries were more prevalent in the ACL-B and PCL-B groups.
Although numerous studies have suggested improved outcomes with early surgery, the timing of surgical intervention in MLKIs remains a debatable issue with no clear consensus of the optimal timing for surgery.2,12,24,27 The prevalence of cartilaginous and meniscal injuries in MLKI has been reported to be nearly 30%, and previous studies have correlated increased intervals of time from injury to surgery with increased rates of chondral and meniscal injury.16,19,33 Some studies suggest that early intervention has been associated with superior clinical and functional outcomes.20,21,29,36 However, others have posited early intervention as a potential predisposition to postoperative stiffness.5,26 Delayed surgery, on the other hand, has been suggested to be advantageous to allow time for swelling to subside, increase range of motion, and promote the healing of key structures such as the capsule, PCL, and collateral ligaments.7,11 Currently, there is no widely accepted time frame that defines acute management versus delayed management. Some studies have described the acute management time frame to be within 3 weeks of injury,13,14,22,37 while others have described it as within 90 days of surgery. 19
A study by Shamrock et al 33 demonstrated that delayed MLKI surgery (>6 weeks after injury) was associated with significantly higher rates of both meniscal and chondral pathology. They reported that 42.9% of patients who underwent surgery >6 weeks from injury had chondral injuries, compared with only 23.2% in the group undergoing surgery <6 weeks, with multifocal chondral lesions significantly more common in the delayed group. In regard to meniscal injury, because Shamrock et al used a 6-week threshold to define acute versus delayed intervention, a direct comparison of meniscal injury rates with the present study remains limited. Nonetheless, these results emphasize the detrimental effects of delaying surgery beyond the acute phase, particularly on the articular cartilage in MLKI.
In contrast to Shamrock et al’s 33 focus on a 6-week threshold for delayed surgery, Krych et al 19 employed a more nuanced time-based stratification of knee dislocations, categorizing patients into intervals from injury to surgery described as early (<90 days), delayed (3-12 months), and chronic (>12 months) intervention groups. Both studies underscore the critical importance of timely surgical intervention. However, Krych et al’s analysis of chronic cases indicates that extended delays lead to more significant chondral injuries across multiple compartments, particularly in the lateral and patellofemoral regions of dislocated knees. 19 Notably, their series included a limited number of cases involving dislocated knees and PCL-B multiligament injuries, as well as those with ≥3 surgically treated ligaments. While Shamrock et al observed a significant increase in meniscal damage with delayed surgery, Krych et al found that meniscal injuries were equally common in both the medial and the lateral compartments across time groups. Given that our study’s time frames were modeled after Krych et al, a direct comparison of results is more appropriate. Furthermore, the present study included more patients in the early and delayed groups, while Krych et al included significantly more patients in the group >365 days. Their findings are similar to the present study, which did not reveal significant differences in meniscal injury rates across surgical time frames of MLKI. 19 However, both studies emphasize that delaying surgery increases the likelihood of progressively worsening cartilage damage as the time interval between injury and surgery increases.
The present study includes a more comprehensive population of MLKIs, defined as any combination of ≥2 injured knee ligaments, and with a larger number of knees overall. Given the variability in how the timing of surgery is defined across studies, and to allow more time for instability events for the purposes of this study, we adopted the time frames outlined by Krych et al. 19 The present study demonstrated higher rates of medial cartilage injury in the acute group. There was a significant difference in the development of medial compartment cartilage injury when comparing the acute to the delayed group, and the acute to the late group, highlighting the detrimental effect of delayed surgical intervention in these cases. Additionally, the lateral compartment demonstrated increased rates of chondral injury when subjected to prolonged instability in the late group when compared with the acute group. However, this difference of rate in the patellofemoral and lateral compartment was not evident between the delayed and late groups. These findings suggest that the 12-month mark, as identified by Krych et al, is indeed critical for the lateral compartment, but our data indicate that the medial compartment is particularly vulnerable even with shorter delays, emphasizing the need for prompt intervention across multiple compartments. It is worth noting that the incidence of lateral compartment injuries was higher in the delayed and late groups compared with the early group in the present study. One possibility is that the lateral compartment experiences less progressive damage with delayed MLKI treatment; another is that the sample sizes in this cohort were insufficient to detect meaningful differences.
In the present study’s analysis of chondral injuries in bicruciate and nonbicruciate MLKIs, patients with both ACL-B and PCL-B nonbicruciate injuries demonstrated higher rates of medial compartment injury when surgery was delayed beyond 90 days after the initial injury. These findings align with previous literature reporting increased medial compartment chondral damage in ACL- and PCL-deficient knees.6,25,35 Additionally, the incidence of injury to cartilage in the patellofemoral compartment, more specifically the trochlea, was significantly increased in bicruciate and ACL-B knees where surgery was delayed beyond 90 days after injury, compared with those undergoing surgery <90 days after injury, consistent with previous studies demonstrating increased rates of injury of these areas in isolated ACL injuries23,32 (see Table 4). Interestingly, time did not seem to affect the rate of chondral injury in the medial compartment in bicruciate injury patterns. There were no differences observed in lateral compartment injuries as it pertains to ligamentous injury patterns. These findings would suggest that, similar to isolated cruciate ligament injuries, delayed treatment may be a risk factor for the development of cartilaginous injury irrespective of the ligamentous injury pattern.
One possible explanation for the observed increase in cartilage damage with delayed surgical intervention, without a corresponding rise in meniscal injury rates, may lie in the distinct biomechanical roles and healing capacities of these tissues. Articular cartilage is avascular and aneural, making it highly susceptible to cumulative damage in the setting of persistent instability and abnormal joint loading, which can occur as patients await surgery. In contrast, the meniscus has limited but present vascular zones and may be more resistant to progressive degeneration over short- to intermediate-term instability. It is plausible that most meniscal tears occur acutely at the time of injury and do not worsen substantially with time, particularly if patients restrict high-impact activity while awaiting surgery. Additionally, cartilage may be more sensitive to subtle microinstability or repetitive loading in subacute and chronic phases, leading to progressive degeneration, whereas meniscal pathology may remain static unless a new mechanical insult occurs. This distinction may also reflect differences in symptomatology, as cartilage damage is often silent until advanced, while meniscal injuries may produce mechanical symptoms earlier, prompting clinical attention sooner, regardless of surgical timing.
Limitations
This study is subject to several limitations. First, the retrospective design may introduce inherent biases related to data collection and missing information, as our analysis relies on accurate and comprehensive medical records. Additionally, because this is retrospective, the chondral observations were only available at the time of surgery. For example, we cannot definitively say that someone treated acutely without chondral injuries did not later develop chondral injuries postoperatively. Despite this, we still believe that the study is impactful in its recognition that patients treated in a late or delayed fashion on average had more chondral damage observed at the time of surgery. Furthermore, a potential selection bias may be present, as MLKIs treated nonoperatively during the study period would not have been captured in our surgical database. These patients may not have developed significant meniscal or cartilaginous injuries and therefore never required surgery, whereas those with early intra-articular pathology likely experienced persistent symptoms that prompted operative intervention. Additionally, this study is limited to patients treated at a single institution, which may affect the generalizability of our findings to other populations or surgical settings. While we adopted the commonly used time frames for acute, delayed, and late surgical intervention, there is no universally accepted definition of these intervals, which may limit comparisons with other studies on MLKIs. Additionally, while injury classifications currently predict injury patterns, they cannot account for mechanism or any other injury characteristics that may affect the study. Another limitation of our study is that we grouped ligament repair and reconstruction together, even though these procedures typically occur at different time points, with repair often performed early and reconstruction delayed, which may introduce selection bias. Furthermore, our late intervention group had a smaller sample size compared with previous research, which may have reduced the power to detect significant differences in some outcomes. Last, inconsistent documentation of intraoperative meniscal and chondral injuries could have potentially introduced variability in the reporting and analysis of these outcomes.
Conclusion
Patients who underwent delayed surgery for their MLKI injuries had more medial and patellofemoral cartilage injuries at the time of surgery than those treated within 30 days of injury.
Footnotes
Final revision submitted March 31, 2025; accepted April 7, 2025.
One or more of the authors has declared the following potential conflict of interest or source of funding: J.F. has received hospitality payments from Stryker, Globus Medical, and Stryker. P.G. has received hospitality payments from Smith & Nephew. J.J.E. has received consulting fees from Medical Device Business Services and DePuy Synthes; hospitality payments from Medical Device Business Services and DePuy Synthes; a grant from Arthrex; and support for education from Arthrex, Gemini Mountain Medical, and Smith & Nephew. T.G.M. has received consulting fees, other compensation, and nonconsulting fees from Arthrex and education payments from Arthrex and Active Medical. S.K.A. has received consulting fees from Stryker. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
Ethical approval for this study was obtained from the University of Utah (No. 174976).
