Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 2: surgical techniques, outcomes and rehabilitation

[Treatment of Injuries to the Posterior Cruciate Ligament]

Compared to the anterior cruciate ligament injury, the rupture of the posterior cruciate Ligament (PCL) is the rarer condition. A high healing potential is attributed to the PCL in the literature, which is why conservative therapy is also considered important in addition to surgical treatment 1. Posterior cruciate ligament rupture is often associated with concomitant injuries. Among other things, up to 70% of cases are associated with accompanying injuries to the posterolateral corner 2. The detection of concomitant injuries has a significant influence on the outcome, as isolated surgical PCL stabilization does not lead to satisfactory results in these cases.

Rates of Subjective Failure After Both Isolated and Combined Posterior Cruciate Ligament Reconstruction: A Study From the Norwegian Knee Ligament Registry 2004-2021

BACKGROUND

Outcomes after posterior cruciate ligament (PCL) reconstruction (PCLR) have been reported to be inferior to those of anterior cruciate ligament reconstruction. Furthermore, combined ligament injuries have been reported to have inferior outcomes compared with isolated PCLR.

PURPOSE/HYPOTHESIS

The purpose of this study was to report on PCLR outcomes and failure rates and compare these outcomes between isolated PCLR and multiligament knee surgery involving the PCL. The hypothesis was that combined PCL injury reconstruction would have higher rates of subjective failure and revision relative to isolated PCLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients with primary PCLR with or without concomitant ligament injuries registered in the Norwegian Knee Ligament Registry between 2004 and 2021 were included. Knee injury and Osteoarthritis Outcome Score (KOOS) totals were collected preoperatively and at 2 years and 5 years postoperatively. The primary outcome measure was failure, defined as either a revision surgery or a KOOS Quality of Life (QoL) subscale score <44.

RESULTS

The sample included 631 primary PCLR procedures, with 185 (29%) isolated PCLR procedures and 446 (71%) combined reconstructions, with a median follow-up time of 7.3 and 7.9 years, respectively. The majority of patients had poor preoperative knee function as defined by a KOOS QoL score <44 (90.1% isolated PCLR, 85.7% combined PCL injuries; P = .24). Subjective outcomes improved significantly at 2- and 5-year follow-up compared with preoperative assessments in both groups (P < .001); however, at 2 years, 49.5% and 46.5% had subjective failure (KOOS QoL <44) for isolated PCLR and combined PCLR, respectively (P = .61). At 5 years, the subjective failure rates of isolated and combined PCLR were 46.7% and 34.2%, respectively (P = .04). No significant difference was found in revision rates between the groups at 5 years (1.9% and 4.6%, respectively; P = .07).

CONCLUSION

Patients who underwent PCLR had improved KOOS QoL scores relative to their preoperative state. However, the subjective failure rate was high for both isolated and multiligament PCLR. Within the first 2 years after surgery, patients who undergo isolated PCLR can be expected to have similar failure rates to patients who undergo combined ligament reconstructions.

Risk factors of failure results after double-bundle reconstruction with autogenous hamstring grafts for isolated posterior cruciate ligament rupture cases

Posterior tibial translation (PTT) after double-bundle posterior cruciate ligament (PCL) reconstruction has sometimes occurred. Purpose of this study is to identify the risk factors for postoperative PTT after double-bundle PCL reconstruction with a hamstring autograft. Comparing the results of bilateral gravity sag view (GSV) at 12 months after surgery, over 5-mm PTT was defined as 'failure' in this study. Of 26 isolated PCL reconstruction cases, over 5-mm PTT was seen in 7 cases (group F: 9.57 ± 1.28 mm), and 19 cases had less than 5 mm (group G: 2.84 ± 1.29 mm). Age, sex, body mass index (BMI), preoperative GSV, posterior slope angle of the tibia, anterolateral bundle (ALB) and posteromedial bundle (PMB) graft diameters, and tibial tunnel diameter were evaluated. The two groups were compared with the 2 × 2 chi-squared test, the Mann Whitney U-test, and Spearman's rank correlation coefficient. Multivariate logistic regression analysis was also performed to determine the risk factor. Statistical significance was indicated as p < 0.01 for correlation with postoperative PTT, and as p < 0.05 for all other comparisons. Mean age (group G 31.8 ± 12.5 vs group F 34.9 ± 15.9 years), sex (male/female: 15/4 vs 3/4), BMI (25.6 ± 4.6 vs 24.9 ± 3.9 kg/m2), preoperative GSV (11.3 ± 2.2 vs 11.6 ± 2.9 mm), PMB diameter (5.37 ± 0.33 vs 5.36 ± 0.48 mm), and tibial tunnel diameter (9.32 ± 0.58 vs 9.29 ± 0.49 mm) showed no significant differences. ALB diameter was significantly greater in group G (7.0 ± 0.5 mm) than in group F (6.5 ± 0.29 mm; p = 0.022). There was also a significant difference in posterior tibial slope angle (group G 9.19 ± 1.94 vs group F 6.54 ± 1.45, p = 0.004). On Spearman rank correlation coefficient analysis, ALB diameter GSV (correlation coefficient: - 0.561, p = 0.003) and posterior tibial slope angle (correlation coefficient: - 0.533, p = 0.005) showed a significant correlation with postoperative PTT. Multivariate logistic regression analysis showed that ALB diameter (OR 19.028; 95% CI 1.082-334.6; p = 0.044) and posterior slope angle of tibia (OR 3.081; 95% CI 1.109-8.556; p = 0.031) were independently associated with postoperative PTT, respectively. In double-bundle PCL reconstruction with hamstring, smaller ALB graft diameter and lower (flatted) tibial slope angle were considered risk factors for postoperative PTT.

Altered knee kinematics after posterior cruciate ligament single-bundle reconstruction-a comprehensive prospective biomechanical in vivo analysis

Purpose: Passive tibiofemoral anterior-posterior (AP) laxity has been extensively investigated after posterior cruciate ligament (PCL) single-bundle reconstruction. However, the PCL also plays an important role in providing rotational stability in the knee. Little is known in relation to the effects of PCL single-bundle reconstruction on passive tibiofemoral rotational laxity. Gait biomechanics after PCL reconstruction are even less understood. The aim of this study was a comprehensive prospective biomechanical in vivo analysis of the effect of PCL single-bundle reconstruction on passive tibiofemoral rotational laxity, passive anterior-posterior laxity, and gait pattern. Methods: Eight patients undergoing PCL single-bundle reconstruction (seven male, one female, mean age 35.6 ± 6.6 years, BMI 28.0 ± 3.6 kg/m2) were analyzed preoperatively and 6 months postoperatively. Three of the eight patients received additional posterolateral corner (PLC) reconstruction. Conventional stress radiography was used to evaluate passive translational tibiofemoral laxity. A previously established rotometer device with a C-arm fluoroscope was used to assess passive tibiofemoral rotational laxity. Functional gait analysis was used to examine knee kinematics during level walking. Results: The mean side-to-side difference (SSD) in passive posterior translation was significantly reduced postoperatively (12.1 ± 4.4 mm vs. 4.3 ± 1.8 mm; p < 0.01). A significant reduction in passive tibiofemoral rotational laxity at 90° knee flexion was observed postoperatively (27.8° ± 7.0° vs. 19.9° ± 7.5°; p = 0.02). The range of AP tibiofemoral motion during level walking was significantly reduced in the reconstructed knees when compared to the contralateral knees at 6-month follow-up (16.6 ± 2.4 mm vs. 13.5 ± 1.6 mm; p < 0.01). Conclusion: PCL single-bundle reconstruction with optional PLC reconstruction reduces increased passive tibiofemoral translational and rotational laxity in PCL insufficient knees. However, increased passive tibiofemoral translational laxity could not be fully restored and patients showed altered knee kinematics with a significantly reduced range of tibiofemoral AP translation during level walking at 6-month follow-up. The findings of this study indicate a remaining lack of restoration of biomechanics after PCL single-bundle reconstruction in the active and passive state, which could be a possible cause for joint degeneration after PCL single-bundle reconstruction.

A modified anatomical posterior cruciate ligament reconstruction technique using the posterior septum and posterior capsule as landmarks to position the low tibial tunnel

BACKGROUND

Lowering the exit position of the tibial tunnel can improve the clinical efficacy of posterior cruciate ligament (PCL) reconstruction, however, there is no unified positioning standard. This study aimed to use novel soft tissue landmarks to create a low tunnel.

METHODS

A total of 14 human cadaveric knees and 12 patients with PCL injury were included in this study. Firstly, we observed the anatomical position between the PCL, posterior septum, and other tissue, and evaluated the relationship between the center of the low tibial tunnel (SP tunnel) and posterior septum and distal reflection of posterior capsule, and using computed tomography (CT) to evaluate distance between the center of the SP tunnel with bony landmarks. Then, evaluated the blood vessels content in the posterior septum with HE staining. Finally, observed the posterior septum and distal reflection of the posterior capsule under arthroscopy to explore the clinical feasibility of creating a low tibial tunnel, and assessed the risk of surgery by using ultrasound to detect the distance between the popliteal artery and the posterior edge of tibial plateau bone cortex.

RESULTS

In all 14 cadaveric specimens, the PCL tibial insertions were located completely within the posterior medial compartment of the knee. The distance between the center of the SP tunnel and the the articular surface of tibial plateau was 9.4 ± 0.4 mm. All SP tunnels retained an intact posterior wall, which was 1.6 ± 0.3 mm from the distal reflection of the posterior capsule. The distances between the center of the SP tunnel and the the articular surface of tibial plateau, the champagne glass drop-off were 9.2 ± 0.4 mm (ICC: 0.932, 95%CI 0.806-0.978) and 1.5 ± 0.2 mm (ICC:0.925, 95%CI 0.788-0.975) in CT image. Compared with the posterior capsule, the posterior septum contained more vascular structures. Last, all 12 patients successfully established low tibial tunnels under arthroscopy, and the distance between the posterior edge of tibial plateau bone cortex and the popliteal artery was 7.8 ± 0.3, 9.4 ± 0.4 and 7.4 ± 0.3 mm at 30°, 60° and 90° flexion angels after filling with water and supporting with shaver in posterior-medial compartment of knee joint.

CONCLUSIONS

A modified low tibial tunnel could be established in the PCL anatomical footprint by using the posterior septum and posterior capsule as landmarks.

Adverse Events After Isolated Posterior Cruciate Ligament Reconstruction: A National Database Study

Background

Optimal management after posterior cruciate ligament (PCL) injury remains an active area of research, as reconstruction is technically challenging and poses unique risks in the posterior knee. Studies have reported variable rates of complications.

Purpose

To describe the rates of readmission, emergency department (ED) visits, and postoperative complications within 90 days of isolated PCL reconstruction (PCLR) in a large, national cohort to better understand the perioperative variables that influence a practitioner's decision of whether to pursue operative versus nonoperative management.

Study Design

Descriptive epidemiology study.

Methods

PCLRs from January 1, 2010, through August 31, 2020, were identified in PearlDiver, a national administrative database. Patients with concomitant ligament surgery and those with fewer than 90 days of postoperative database activity were excluded. Deep vein thromboses, pulmonary embolisms, surgical site infections, compartment syndrome, and vascular events within 90 days of surgery were identified, as were 90-day readmissions and ED visits. Logistic regression models were built in PearlDiver to calculate odds ratios (ORs) for ED utilization.

Results

The final cohort consisted of 1154 patients with isolated PCLR (mean age, 34 ± 16 years; 62% male). Most patients were located in the Southern United States (n = 417; 36.1%), and most had commercial insurance (n = 992; 86%). The 90-day rates of adverse events were as follows: deep vein thrombosis (13; 1.1%), pulmonary embolism (19; 1.6%), surgical site infection (<11; <1%), compartment syndrome (<11; <1%), vascular event (<11; <1%), readmission (13, 1.1%), and ED utilization (99; 8.6%). The majority of emergency department visits (52%) occurred in the first 2 weeks postoperatively. Predictive factors for ED utilization included Elixhauser Comorbidity Index score (OR = 1.31 per 2-point increase) and Medicaid insurance (OR = 2.03 relative to commercial insurance).

Conclusion

The current study reported rates of adverse events after isolated PCLR in a large, national cohort. The results provide important context for decisions about optimal management of PCL injury.

Decreased posterior tibial slope is a risk factor for primary posterior cruciate ligament rupture and posterior cruciate ligament reconstruction failure: A systematic review

PURPOSE

To determine bony knee morphological factors associated with primary posterior cruciate ligament (PCL) rupture or PCL graft failure after PCL reconstruction.

METHODS

Three databases, namely MEDLINE, PubMed and EMBASE, were searched on 30th May 2023. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data such as receiver operating characteristic curve parameters, as well as p-values for comparisons of values between patients with PCL pathology and control patients, were recorded.

RESULTS

Nine studies comprising 1054 patients were included. Four studies reported that patients with PCL injury had flatter medial posterior tibial slopes (MTS) than controls, with mean values of 4.3 (range: 3.0-7.0) and 6.5 (range: 5.0-9.2) degrees, respectively. Two studies reported an MTS cutoff value ranging below 3.90-3.93° being a significant risk factor for primary PCL rupture or PCL graft failure. Two studies reported that shallow medial tibial depths were associated with primary PCL rupture, with mean values of 2.1 (range: 2.0-2.2) and 2.6 (range: 2.4-2.7) mm in PCL injury and control groups, respectively. Stenotic intercondylar notches and femoral condylar width were not consistently associated with PCL injuries.

CONCLUSION

Decreased MTS is associated with primary PCL rupture and graft failure after PCL reconstruction with values below 3.93° being considered as a significant risk factor. Less common risk factors include shallow medial tibial depth, while femoral condylar width and parameters with regards to the intercondylar notch, such as notch width, notch width index and intercondylar notch volume, demonstrated conflicting associations with primary or secondary PCL injuries.

LEVEL OF EVIDENCE

Level III.

Outcome Analysis of Posterior Cruciate Ligament Injuries: A Narrative Review

The primary posterior stabilizer of the knee is the posterior cruciate ligament (PCL), the largest intra-articular ligament in the human knee. One of the four primary ligaments of the knee joint, the PCL, serves to support the tibia on the femur. An extreme force applied anteriorly to the proximal tibia of the flexed knee results in trauma to the PCL. Dashboard injuries, which occur when the knee is driven into the dashboard after a collision with a motor vehicle, are frequent causes. Grade 1 and 2 acute injuries are often addressed conservatively due to the PCL's natural capacity for mending. If a grade 3 injury occurs, a cautious trial can be conducted on elderly or low-demand patients. When standard treatment for isolated grade 3 injuries has failed, surgery is advised. Single-bundle or double-bundle techniques using either transtibial tunnel or tibial inlay techniques are among the reconstruction approaches. Restoring the natural kinematics of the knee and forestalling persistent posterior and mixed rotatory knee laxity are the ultimate goals of treating PCL injuries through a personalized strategy. These injuries may become more common in the future as more people participate in sports. As a result of ongoing instability, discomfort, diminished function, and the emergence of inflammatory and degenerative disorders of joints, PCL rips are becoming more well-acknowledged as a cause of morbidity and decreased function.

The tibial tunnel drilling angles of 60° provided a lower ultimate load to failure on a single bundle posterior cruciate ligament graft using interference screw fixation compared to 30°/45°

PURPOSE

To biomechanically compare the initial fixation strength of grafts among three tibial tunnel angles (30°/45°/60°) in transtibial posterior cruciate ligament (PCL) reconstruction.

METHODS

A series of transtibial PCL reconstruction models were established with porcine tibias and bovine tendons. Specimens were randomly assigned to three groups according to the angles between the tibial tunnel and the perpendicular line of the tibial shaft: Group A (30°, n = 12), Group B (45°, n = 12), and Group C (60°, n = 12). The area of the tunnel entrance, the segmental bone mineral density (sBMD) of the graft fixation site of the tibia and the maximum insertion torque of the interference screw were measured. Finally, load to failure tests were carried out on the graft-screw-tibia constructs at the same rate.

RESULTS

Ultimate load to failure in Group C (335.2 ± 107.5 N) was significantly lower than that in Group A (584.1 ± 127.9 N, P < 0.01) and Group B (521.9 ± 95.9 N, P < 0.01). There were no significant differences between biomechanical properties of Groups A and B (n.s.). The posterior part fractures of the tibial tunnel exit occurred in eight specimens of Group C. In addition, the ultimate load was proven to be related to insertion torque (rho = 0.7, P < 0.01), sBMD (rho = 0.7, P < 0.01), and the area of the tunnel entrance (rho =- 0.4, P = 0.01).

CONCLUSION

The ultimate load to failure was significantly lower in tibial PCL interference screw fixation for tunnels drilled at 60° compared to 30°/45°. In addition, the ultimate load was significantly correlated with insertion torque, sBMD and the area of the tunnel entrance. Given that the load to failure of distal fixation may not be sufficient for early postoperative rehabilitation, a 60° tunnel should not be recommended to drill in tibia during PCL reconstruction.

Decreased medial posterior tibial slope is associated with an increased risk of posterior cruciate ligament rupture

PURPOSE

It remains unclear whether there is an association between posterior cruciate ligament (PCL) rupture and the medial posterior tibial slope (MTS) or lateral posterior tibial slope (LTS). The present case-control study aimed to investigate a possible association between primary PCL rupture and MTS or LTS measured by magnetic resonance imaging (MRI).

METHODS

A retrospective case-control study was conducted. Patients with primary PCL ruptures but not with anterior cruciate ligament injuries, were 1:1 matched by age and sex to a control group with no evidence of knee ligament injuries. Knee MRI was used to measure the MTS and LTS. In addition, the receiver operating characteristic (ROC) analysis was performed to identify an optimal cut-off value of the MTS and/or LTS.

RESULTS

In total, 46 patients with PCL ruptures (32 males, 14 females) and 46 controls (32 males, 14 females) were included in this study. The MTS was significantly lower in the patients with PCL ruptures (3.0° ± 2.2°) than in the control group (5.1° ± 2.3°, p < 0.001). The mean LTS/MTS ratio was significantly higher in patients with PCL ruptures (2.6 ± 2.5) than in the control group (1.3 ± 1.3, p = 0.001). However, the LTS was not significantly different between patients with PCL ruptures and the controls (4.4° ± 2.3° vs. 5.3° ± 2.6°, n.s.). After the MTS was determined to be a significant predictor, the ROC analysis was performed. The ROC analysis revealed the most accurate MTS cut-off of < 3.9°, with a sensitivity of 76.1% and a specificity of 73.9%.

CONCLUSION

A decreased MTS and an increased LTS/MTS ratio are associated with an increased risk of primary PCL rupture. People with MTS < 3.9° are particularly at risk for PCL ruptures, and prevention and intervention programs for PCL ruptures should be developed and targeted towards them.

LEVELS OF EVIDENCE

Level III.

Association Between Tunnel Position, Tunnel Angle, Graft Signal Intensity, and Graft Thickness in the Reconstructed Posterior Cruciate Ligament

Background

An appropriate tunnel position, tunnel angle, and tunnel-graft angle are important factors for maintaining the stability and mechanical properties of a posterior cruciate ligament (PCL) graft.

Purpose

To evaluate the association between tunnel position, tunnel angle, graft signal intensity ratio (SIR), and graft thickness after remnant-preserving PCL reconstruction.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Included were patients who had undergone remnant-preserving single-bundle PCL reconstruction using a tibialis anterior allograft between March 2014 and September 2020 and who had minimum 12-month postoperative magnetic resonance imaging scans. Tunnel position and angle were evaluated via 3-dimensional computed tomography, and their association with graft SIR on both the femoral and the tibial sides was determined. Graft thickness and SIR at 3 areas of the graft were evaluated and compared, and their association with tunnel-graft angle was also determined.

Results

Overall, 50 knees (50 patients; 43 male, 7 female) were included. The mean time to postoperative magnetic resonance imaging was 25.8 ± 15.8 months. The mean SIR of the graft's midportion was higher compared with that of the proximal and distal portions (P = .028 and P < .001, respectively), and the SIR of the proximal portion was higher compared with that of the distal portion (P = .002). The femoral tunnel-graft angle was more acute than the tibial tunnel-graft angle (P = .004). A more anteriorly and distally located femoral tunnel led to a less acute femoral tunnel-graft angle (P = .005) and a decreased SIR of the proximal portion (P = .040), and a more laterally located tibial tunnel was associated with a less acute tibial tunnel-graft angle (P = .024) and a reduced SIR of the distal portion (P = .044). The mean thicknesses of the graft's midportion and distal portion were larger than that of the proximal portion (P < .001). The SIR of the graft's midportion was positively correlated with its thickness (r = 0.321; P = .023).

Conclusion

The SIR of the proximal portion of the graft around the femoral tunnel was higher than that of the distal portion around the tibial tunnel. An anteriorly and distally positioned femoral tunnel and a laterally positioned tibial tunnel resulted in less acute tunnel-graft angles that were associated with decreased signal intensity.

Delayed multiligament PCL reconstruction is associated with a higher prevalence of intraarticular injury and may influence treatment

BACKGROUND

The aim of this study was to investigate differences in concomitant injury patterns and their treatment in patients undergoing early (≤ 12 weeks) and delayed (> 12 weeks) primary multiligament posterior cruciate ligament (PCL) reconstruction (PCL-R).

METHODS

This study was a retrospective chart review of patients undergoing primary multiligament PCL-R at a single institution between 2008 and 2020. Multiligament PCL-R was defined as PCL-R and concurrent surgical treatment of one or more additional knee ligament(s). Exclusion criteria included isolated PCL-R, PCL repair, and missing data for any variable. Patients were dichotomized into early (≤ 12 weeks) and delayed (> 12 weeks) PCL-R groups based on the time elapsed between injury and surgery. Between-group comparison of variables were conducted with the Chi-square, Fisher's exact, and independent samples t-tests.

RESULTS

A total of 148 patients were eligible for analysis, with 57 (38.5%) patients in the early and 91 (61.1%) patients in the delayed multiligament PCL-R groups. Concomitant LCL/PLC reconstruction (LCL-R/PLC-R) was performed in 55 (60%) of delayed multiligament PCL-Rs and 23 (40%) of early PCL-Rs (p = 0.02). Despite similar rates of meniscus injury, concomitant meniscus surgery was significantly more prevalent in the early (n = 25, 44%) versus delayed (n = 19, 21%) multiligament PCL-R group (p = 0.003), with a significantly greater proportion of medial meniscus surgeries performed in the early (n = 16, 28%) compared to delayed (n = 13, 14%) PCL-R group (p = 0.04). The prevalence of knee cartilage injury was significantly different between the early (n = 12, 24%) and delayed (n = 41, 46%) multiligament PCL-R groups (p = 0.01), with more frequent involvement of the lateral (n = 17, 19% vs. n = 3, 5%, respectively; p = 0.04) and medial (n = 31, 34% vs. n = 6, 11%, respectively; p = 0.005) femoral condyles in the delayed compared to the early PCL-R group.

CONCLUSIONS

Given higher rates of chondral pathology and medial meniscus surgery seen in delayed multiligament PCL-R, early management of PCL-based multiligament knee injury is recommended to restore knee stability and potentially prevent the development of further intraarticular injury.

LEVEL OF EVIDENCE

Level III.

Clinical, patient-reported, radiographic and magnetic resonance imaging findings 11 years after acute posterior cruciate ligament injury treated non-surgically

BACKGROUND

Long-term consequences of posterior cruciate ligament (PCL) injury such as persistent posterior tibial translation and risk of osteoarthritis development are unclear. Additionally, little data is available describing the natural history of structural morphology of the ruptured PCL. The purpose of the study was to determine the long-term outcome after non-operatively treated PCL injury.

METHODS

Over 6-years, all acute knee injuries were documented by subacute MRI (median 8 days [5-15, 25th - 75th percentile] from injury to MRI). Twenty-six patients with acute PCL injury were identified of whom 18 (69%) participated in the long-term follow-up after 11 years. Follow-up included radiographic posterior tibial translation (RPTT) determined using the Puddu axial radiograph. weight-bearing knee radiographs, MRI and KOOS (Knee injury and Osteoarthritis Outcome Score).

RESULTS

On subacute MRI, 11 knees displayed total and 7 partial ruptures. At 11 (SD 1.9) years, the median RPTT was 3.7 mm (1.5-6.3, 25th - 75th percentile). Seven knees displayed radiographic osteoarthritis approximating Kellgren-Lawrence grade ≥ 2. All follow-up MRIs displayed continuity of the PCL. Patients with more severe RPTT (> 3.7 mm), had worse scores in the KOOS subscales for symptoms (mean difference 14.5, 95% CI 7-22), sport/recreation (30, 95% CI 0-65) and quality of life (25, 95% CI 13-57) than those with less severe RPTT (≤ 3.7 mm). This was also the case for the KOOS₄ (22, 95% CI 9-34).

CONCLUSION

Acute PCL injuries treated non-surgically display a high degree of PCL continuity on MR images 11 years after injury. However, there is a large variation of posterior tibial translation with higher values being associated with poorer patient-reported outcomes.

Safe femoral tunnel drilling angles avoid injury to the medial and posteromedial femoral anatomic structures during single-bundle posterior cruciate ligament reconstruction with the inside-out technique

PURPOSE

To investigate the relationship between the medial and posteromedial femoral anatomic structures and the femoral tunnel exit produced by different tunnel orientations when creating the femoral tunnel for posterior cruciate ligament reconstruction (PCLR) using the inside-out (IO) technique and to estimate safe tunnel orientations to minimize the risk of iatrogenic injury to these structures.

METHODS

Eleven cadaveric knees were used. The medial and posteromedial aspects of each knee joint were dissected to reveal the "safe zone," which is a bony area that avoids the distribution or attachment of at-risk structures (MCL, PMC structures, and articular cartilage), while remaining 10 mm away from the articular cartilage. The hypothesis of this study was that by creating the femoral tunnel at specific angles using the IO technique, the tunnel outlet would be as close to the safe zone as possible, protecting the at-risk structures from damage. Femoral tunnels were drilled at 20 different angle combinations on each specimen: 0°, 15°, 30°, 45°, and 60° relative to a line parallel to the transepicondylar axis in the axial plane, as well as 15°, 30°, 45°, and 60° relative to a line parallel to the femoral axis in the coronal plane. The positional relationship between each tunnel exit and the safe zone was recorded, and the shortest distance between the exit center and the safe zone boundary was measured.

RESULTS

The risk of iatrogenic injury differed depending on the drilling orientation (χ² = 168.880, P < 0.001). Femoral drilling angle combinations of 45/45°, 45/60°, 60/30°, 60/45°, and 60/60° (axial/coronal) were considered relatively safer than other orientations (P < 0.05). The shortest distance between the tunnel exit and the safe zone boundary was negatively correlated with the angle in the axial plane (P < 0.001, r = - 0.810).

CONCLUSIONS

When creating the IO femoral tunnel for single-bundle PCL reconstruction, angle combinations of 45/45°, 45/60°, 60/30°, 60/45°, and 60/60° (axial/oblique coronal) could be utilized to prevent at-risk structures from being damaged. The drilling angles and the safe zone can be employed to optimize the femoral tunnel in PCLR.

Different femoral tunnel placement in posterior cruciate ligament reconstruction: a finite element analysis

BACKGROUND

At present, there is no consensus on the optimal biomechanical method for Posterior cruciate ligament (PCL) reconstruction, and the "critical corner" that is produced by the femoral tunnel is currently considered to be one of the main reasons for PCL failure. Thus, the purpose of this study was to identify one or several different tunnels of the femur, thereby reducing the influence of the "critical corner" without reducing the posterior stability of the knee.

METHODS

CT and MRI data of the knee joint of a healthy adult man were collected, and computer-related software was used to reconstruct the finite element model of the knee joint, to provide different properties to different materials and to allow for the performance of a finite element analysis of the reconstructed model. The position of the femoral tunnel was positioned and partitioned according to anatomical posture, and three areas were divided (the antero-proximal region, the antero-distal region and the posterior region). In addition, we applied a posterior tibial load of 134 N to the reconstructed model, recorded and compared different tunnels of the femur, conducted peak stress at the flexion of the knee joint of 0°, 30°, 60° and 90°, and elicited the displacement of the proximal tibia.

RESULTS

Among the 20 different femoral tunnels, the graft peak stress was lower in tunnels 4, 12 and 18 than in the PCL anatomical footpath tunnel 13, especially at high flexion angles (60° and 90°). These three tunnels did not increase the posterior displacement of the proximal tibia compared with the anatomical footpath tunnel 13.

CONCLUSION

In summary, among the options for PCL reconstruction of the femoral tunnel, the tunnels located 5 mm distal to the footprint and 5 mm anterior to the footprint could reduce the peak stress of the graft; additionally, it may reduce the "critical corner" and was shown to not reduce the posterior stability of the knee joint.

Influence of the Tibial Tunnel Angle and Posterior Tibial Slope on "Killer Turn" during Posterior Cruciate Ligament Reconstruction: A Three-Dimensional Finite Element Analysis

This study aimed to evaluate the influence of various posterior tibial slopes (PTSs) and tibial tunnel angles (TTAs) on "killer turn" in posterior cruciate ligament (PCL) reconstruction by using three-dimensional finite element analysis (FEA). The study models were created using computed tomography images of a healthy young Asian male. Using SolidWorks, PCL grafts and tibial bone tunnels at different tibial drilling angles (30°, 45°, 60°) were developed. Anterior opening wedge high tibial osteotomy (aOW-HTO) was performed to evaluate the influence of the PTS (+8°, +4°, native, -4°, -8°). An FEA was performed utilizing the ANSYS software program. In the same PTS model, the peak of the equivalent Von Mises stress in PCL grafts decreased as the angle of the TTA increased. In the same TTA model, the peak of the Von Mises in PCL grafts decreased as the PTS angle increased. The "high-contact stress area" (contact stress greater than 10 MPa) was diminished when the TTA and PTS were increased. aOW-HTO was used to steepen the PTS, and a larger TTA may reduce the stress at the "killer turn" during PCL reconstruction. In conclusion, the study findings suggest that using aOW-HTO to steepen the PTS and a larger TTA may reduce the stress at the "killer turn" during PCL reconstruction. The usefulness and safety of this surgical procedure need to be evaluated in future clinical studies.

Return to Play after Posterior Cruciate Ligament Injuries

PURPOSE OF REVIEW

Posterior cruciate ligament injuries can be treated conservatively with a structured rehabilitation program or with surgical reconstruction. Treatment algorithms are based on a variety of factors including the patient's presentation, physical exam, and desired level of activity. The goal is to return the patient to their athletic pursuits with a stable and pain-free knee. Return to play and activities should be individualized based on the patient's injury and progression through rehabilitation. This article provides a review of the current treatments for posterior cruciate ligament injuries and the respective rehabilitation protocols, outcomes after each treatment option, and specific return to play criteria.

RECENT FINDINGS

Current research shows excellent outcomes and return to play with conservative treatment of isolated posterior cruciate ligament injuries. Return to play algorithms stress the importance of quadriceps strengthening throughout the recovery process and emphasize inclusion of plyometrics and sport-specific training. Rehabilitation plays a critical role in the outcome after posterior cruciate ligament injury and the ability to return to athletics. The primary focus of post-injury or post-operative rehabilitation is to restore function, as it relates to range of motion, strength, and proprioception, while mitigating swelling and pain. The patients' desired sport and level of play dictate return to play timelines. The literature supports the use of non-operative management of isolated PCL injuries in athletes and non-athletes with excellent functional and patient-reported outcomes.

Global variation in isolated posterior cruciate ligament reconstruction

Purpose

In the setting of persistent instability or failed non-operative management, surgical reconstruction is commonly recommended for isolated posterior cruciate ligament (PCL) tears. The purpose of this study was to systematically review published studies to evaluate regional variation in the epidemiology of and surgical approaches to primary, isolated PCL reconstruction.

Methods

A systematic review was performed in June 2022 to identify studies examining operative techniques during primary, isolated PCL reconstruction. Collected variables consisted of reconstruction technique, graft type, graft source, tibial reconstruction technique, femoral and tibial drilling and fixation methods, and whether the remnant PCL was preserved or debrided. Studies were classified into four global regions: Asia, Europe, North America, and South America.

Results

Forty-five studies, consisting of 1461 total patients, were identified. Most of the included studies were from Asia (69%, n = 31/45). Single bundle reconstruction was more commonly reported in studies out of Asia, Europe, and North America. Hamstring autografts were utilized in 51.7% (n = 611/1181) of patients from Asia and 60.8% (n = 124/204) of patients from Europe. Trans-tibial drilling and outside-in femoral drilling were commonly reported in all global regions. The PCL remnant was generally debrided, while remnant preservation was commonly reported in studies from Asia.

Conclusion

Surgical treatment of isolated PCL injuries varies by region, with the majority of published studies coming from Asia. Single-bundle reconstruction with hamstring autograft through a trans-tibial approach is the most commonly reported technique in the literature, with males reported to undergo isolated reconstruction more often than females.

Level of Evidence

Systematic review, Level IV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00541-4.

Good clinical and radiological results following remnant-preserving posterior cruciate ligament reconstruction: a systematic review

PURPOSE

The objective of this systematic literature review was to report the results and complications of recent remnant preservation techniques in posterior cruciate ligament (PCL) reconstruction.

METHODS

A systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two independent reviewers searched the PubMed, Scopus, Embase, and Cochrane Library databases using the terms "posterior cruciate ligament" or "PCL" and "remnant preserving." The outcome measures extracted from the studies were the Lysholm score, the International Knee Documentation Committee's (IKDC) subjective and objective scores, Tegner scores, Orthopädische Arbeitsgruppe Knie (OAK) rate of return to sports, and rate of complications. Data were also extracted from studies that used stress radiographs to perform a quantitative assessment of the preoperative and postoperative anteroposterior stability.

RESULTS

The systematic review included 13 studies. The patient cohort of consisted of 643 participants (544 [84.6%] men and 99 [15.4%] women) with a mean age of 32.9 ± 4.0 years. The mean postoperative follow-up was 34.5 ± 10.9 months (range: 24-96 months), while the mean time from injury to surgery was 14.4 ± 9.9 months (range: 0-240 months). All studies reported clinically significant improvement at final follow-up, as evident from the measured subjective and objective IKDC scores, Lysholm score, Tegner score, and OAK rate. Only three studies reported return to sports activity, with a mean percentage of 90.8% (99/109). All studies showed a significant improvement in posterior translation, from 11.5 ± 1.2 mm to 3.3 ± 1.1 mm, using radiography (side-to-side difference). This systematic review revealed 13 (2.0%) failures and 33 (5.1%) minor complications: 10 (1.6%) cases of stiffness, 21 (4.9%) screws removal, 1 (0.2%) injury of the peroneal nerve, and 1 (0.2%) fibular fracture.

CONCLUSIONS

With the currently available data, all studies included in the review on posterior cruciate ligament reconstruction with remnant preservation demonstrated satisfactory outcomes at mid-term follow-up (> 24 months), despite varying surgical techniques and graft types, and intervals from injury to surgery. For clinical relevance, standard PCL reconstruction is a highly effective operation in terms of improvement in functional status, knee stability, quality of life, and cost effectiveness. The remnant preservation technique requires more comprehensive diagnostic assessments of the PCL remnant patterns and more complicated surgical procedures. Given the absence so far of high quality studies with long-term follow-up, the remnant-preserving techniques should be recommended only by experienced knee arthroscopic surgeons.

LEVEL OF EVIDENCE

Level IV.

STUDY REGISTRATION

reviewregistry1376- www.researchregistry.com .

Low posterior tibial slope is associated with increased risk of PCL graft failure

PURPOSE

To evaluate the effect of posterior tibial slope (PTS) on patient-reported outcomes (PROs) and posterior cruciate ligament (PCL) graft failure after PCL reconstruction.

METHODS

Patients undergoing PCL reconstruction with a minimum 2-year follow-up were included in this retrospective cohort study. A chart review was performed to collect patient-, injury-, and surgery-related data. Medial PTS was measured on preoperative lateral radiographs. Validated PROs, including the International Knee Documentation Committee Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score, Lysholm Score, Tegner Activity Scale, and Visual Analogue Scale for pain, were collected at final follow-up. A correlation analysis was conducted to assess the relationship between PTS and PROs. A logistic regression model was performed to evaluate if PTS could predict PCL graft failure.

RESULTS

Overall, 79 patients with a mean age of 28.6 ± 11.7 years and a mean follow-up of 5.7 ± 3.3 years were included. After a median time from injury of 4.0 months, isolated and combined PCL reconstruction was performed in 22 (28%) and 57 (72%) patients, respectively. There were no statistically significant differences in PROs and PTS between patients undergoing isolated and combined PCL reconstruction (non-significant [n.s.]). There were no significant correlations between PTS and PROs (n.s.). In total, 14 (18%) patients experienced PCL graft failure after a median time of 17.5 months following PCL reconstruction. Patients with PCL graft failure were found to have statistically significantly lower PTS than patients without graft failure (7.0 ± 2.3° vs. 9.2 ± 3.3°, p < 0.05), while no differences were found in PROs (n.s.). PTS was shown to be a significant predictor of PCL graft failure, with a 1.3-fold increase in the odds of graft failure for each one-degree reduction in PTS (p < 0.05).

CONCLUSIONS

This study showed that PTS does not affect PROs after PCL reconstruction, but that PTS represents a surgically modifiable predictor of PCL graft failure.

LEVEL OF EVIDENCE

III.

Application of CT-MRI Fusion-Based Three-Dimensional Reconstruction Technique in the Anatomic Study of Posterior Cruciate Ligament

Objective

During PCL reconstruction surgery, precise and personalized positioning of the graft tunnel is very important. In order to obtain patient‐specific anatomical data, we established a three‐dimensional knee joint fusion model to provide a unified imaging strategy, as well as anatomical information, for individualized and accurate posterior cruciate ligament (PCL) reconstruction.

Methods

This is an exploration study. From January 2019 to January 2020, 20 healthy adults randomly were enrolled and assessed via CT and MRI imaging. A three‐dimensional fusion model of the knee joint was generated using the modified MIMIMICS and image fusion software. On the fused image, the areas of the femoral and tibial PCL footprint of both knees were measured. The anatomical center of the PCL footprint was measured at the femoral and tibial ends. The relevant bony landmarks surrounding the PCL femoral and tibial attachment were also measured. Paired t‐tests were employed for all statistical analyzes, and p < 0.05 was considered as statistically significant.

Results

All 20 subjects achieved successful image fusion modeling and measurement, with an average duration of 12 h. The lengths of the LF1‐LF3 were 32.1 ± 1.8, 6.8 ± 2.5, and 23.3 ± 2.1 mm, respectively. The lengths of the LT1‐LT3 were 37.3 ± 3.3, 45.6 ± 5.3, and 6.0 ± 1.2 mm, respectively. The distances between the tibial PCL center of the left knee to the medial groove, champagne‐glass drop‐off, and the apex of the medial intercondylar were 8.4 ± 2.4, 9.2 ± 1.8, and 15.3 ± 1.4 mm, respectively, and the corresponding distances from the right knee were 8.0 ± 2.0, 9.4 ± 2.2, and 16.1 ± 1.8 mm, respectively. We observed no difference between the bilateral sides, in terms of the distance from the PCL center to the PCL attachment‐related landmark, under arthroscopic guidance. The area of the femoral and tibial PCL footprints on the left knee were 115.3 ± 33.5 and 146.6 ± 24.4 mm², respectively, and the corresponding areas on the right knee were 121.8 ± 35.6 and 142.8 ± 19.5 mm², respectively. There was no difference between the bilateral sides in terms of the PCL footprint areas.

Conclusion

In the fusion image, the PCL attachment center and relevant bony landmarks which can be easily identified under arthroscopy can be accurately measured. The model can also obtain personalized anatomical data of the PCL on the unaffected side of the patient, which can guide clinical PCL reconstruction.

Midterm Outcomes After Revision Posterior Cruciate Ligament Reconstruction With a Single-Bundle Transtibial Autograft

Background:

There is a lack of consensus regarding the optimal technique for revision posterior cruciate ligament (PCL) reconstruction.

Purpose:

To evaluate midterm outcomes after revision PCL reconstruction using a single-bundle transtibial autograft.

Study Design:

Case series; Level of evidence, 4.

Methods:

We reviewed 17 patients who underwent revision PCL reconstruction performed in our medical center by a single surgeon from 2003 to 2016. The cohort included 12 male and 5 female patients with a mean age of 31.3 years (range, 17-48 years). All of the patients underwent single-bundle transtibial reconstruction using the same surgical technique and were reviewed at a minimum of 4 years postoperatively. Preoperative and postoperative posterior stress radiography was performed. The preoperative tibial slope and tibiofemoral angle were also measured. Preoperative and postoperative functional outcomes were evaluated using the International Knee Documentation Committee (IKDC) subjective and objective scores as well as the Lysholm score.

Results:

The most common factor that contributed to the failure of primary surgery was misplaced tunnels, especially on the femoral side. There were 2 patients who had grade 2 laxity preoperatively, and 15 patients had grade 3 laxity preoperatively. At the latest follow-up, all 17 patients had grade 1 laxity. On posterior stress radiography, posterior displacement improved from 10.8 ± 2.1 mm preoperatively to 2.9 ± 1.1 mm at the latest follow-up (P < .001). The IKDC subjective score improved from 34.9 ± 6.8 preoperatively to 75.3 ± 15.7 postoperatively (P < .001), and the Lysholm score improved from 38.1 ± 10.0 preoperatively to 88.5 ± 7.6 postoperatively (P < .001). All patients reached the minimal clinically important difference (MCID) for the Lysholm score, and 94% reached the MCID for the IKDC subjective score, with 65% reaching the Patient Acceptable Symptom State.

Conclusion:

According to the findings of this study, arthroscopic revision PCL reconstruction with a single-bundle transtibial autograft offered satisfactory outcomes at midterm follow-up.

Sports activity and quality of life improve after isolated ACL, isolated PCL, and combined ACL/PCL reconstruction

PURPOSE

To compare patient-reported outcomes following isolated anterior cruciate ligament reconstruction (ACL-R), isolated posterior cruciate ligament reconstruction (PCL-R), and combined ACL-R and PCL-R (ACL/PCL-R), at a minimum follow-up of 2 years.

METHODS

This was a prospective observational registry cohort study based on the Swedish National Knee Ligament Registry. Patients undergoing isolated ACL-R, isolated PCL-R, and combined ACL/PCL-R between 2005 and 2019 were eligible for inclusion. Demographic characteristics as well as injury- and surgery-related data were queried from the SNKLR. To evaluate functional outcomes, the Knee Injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at 1- and 2-year follow-ups and compared between the treatment groups.

RESULTS

In total, 45,169 patients underwent isolated ACL-R, 192 patients isolated PCL-R, and 203 patients combined ACL/PCL-R. Preoperatively, and at the 1- and 2-year follow-ups, KOOS subscales were highest for the isolated ACL-R group, followed by the isolated PCL-R, and lowest for the combined ACL/PCL-R groups. Significant improvements were observed across all treatment groups in the majority of KOOS subscales between the preoperative, and 1- and 2-year follow-ups. All treatment groups showed the greatest improvements between the preoperative and 2-year follow-ups in the knee-related quality of life (mean improvement: isolated ACL-R, + 28 points; isolated PCL-R, + 23 points; combined ACL/PCL-R, + 21 points) and the function in sport and recreation (mean improvement: isolated ACL-R, + 26 points; isolated PCL-R, + 20 points; combined ACL/PCL-R, + 19 points) subscales.

CONCLUSION

Clinically relevant improvements in knee function can be expected after isolated ACL-R, isolated PCL-R, and combined ACL/PCL-R. Functional improvements were particularly pronounced in the KOOS function in sport and recreation subscale, indicating the importance of knee stability for sports activity. This study facilitates more comprehensive patient education about functional expectations after surgical treatment of isolated and combined ACL and PCL injuries.

LEVEL OF EVIDENCE

Level 2.

Posterior cruciate ligament reconstruction with independent internal brace reinforcement: surgical technique and clinical outcomes with a minimum two year follow-up

PURPOSE

We developed an augmentation technique for PCL reconstruction with independent internal brace reinforcement and evaluated the functional outcome after PCL reconstruction employing autologous hamstrings augmented with an internal brace system for patients with isolated or combined grade 3 posterior instability who were treated with this technique.

METHODS

From January 2016 to January 2018, patients with isolated or combined grade 3 PCL tears who underwent single-bundle PCL reconstruction using autologous hamstrings augmented with independent internal braces were studied. The function of the operated knee was evaluated according to the International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity score. The patients were asked the level of returned to their previous sport. Posterior knee laxity was examined with a KT-1000 arthrometer, and data on range of motion (ROM), re-operation, and other complications were collected.

RESULTS

A total of 33 consecutive patients who received single-bundle PCL reconstruction using autologous hamstrings augmented with independent internal braces with a minimum two years follow-up were included in this study. Two patients had undergone this procedure during the study period and were not included in this study (one had combined bone fractures, and one patient had previous meniscus surgery). Thirty-one patients were available for final analysis. The mean follow-up was 45.35 ± 10.88 months (range 29-66 months). The average IKDC subjective knee evaluation scores from 51.65 ± 12.35 to 84.52 ± 6.42, the Lysholm score from 53.90 ± 11.86 to 85.68 ± 4.99, and the Tegner score from 2.81 ± 0.79 to 6.71 ± 1.83 (P < 0.05 for all). The mean total posterior side-to-side difference in knee laxity, assessed using a KT-1000 arthrometer, decreased from 12.13 ± 2.66 mm pre-operatively to 1.87 ± 0.56 mm post-operatively at 70° (P < 0.05). Most patients (29/31) had normal or near normal knee ROM post-operatively; two patients revealed a 6-15° loss of knee flexion compared with the contralateral knee. Twenty-nine patients (93.55%) returned to a normal daily exercise level. Twenty-three patients (74.19%) returned to competitive sports with high-level sports (Tegner score of 6 or above; eleven patients (35.48%) reported to be on the same level as well as the Tegner level); six patients (19.35%) returned to recreational sports (Tegner score of 4 or 5). Two patients had Tegner scores of 2 and 3, indicating poor function level. No patient needed PCL revision surgery during the follow-up period.

CONCLUSION

Single-bundle PCL reconstruction with internal brace augmentation for PCL injury exhibited satisfactory posterior stability and clinical outcomes in patients with isolated or combined grade 3 PCL injuries at a minimum two year follow-up.

Operative management of isolated posterior cruciate ligament injuries improves stability and reduces the incidence of secondary osteoarthritis: a systematic review

PURPOSE

To evaluate the evidence for operative and non-operative management of isolated posterior cruciate ligament (PCL) injuries.

METHODS

Using Pubmed, EMBASE and Cochrane databases, a systematic review was conducted of studies investigating the treatment of isolated PCL injuries published until July 2020. Quality assessment was performed with the Cochrane risk of bias tool (level I), the Newcastle-Ottowa Scale (level II-III) and the National Institute of Health quality assessment tool (level IV). Clinical outcome measures included residual laxity, return to sports, patient-reported outcome measures, subsequent articular degeneration and complications.

RESULTS

Twenty-seven studies [23 case series, 2 case-control, 1 cohort study and 1 randomized controlled trial (RCT)] including 5197 patients (5199 knees) with a mean age of 29.5 ± 3.6 years (range 15-68) fulfilled the study requirements. Significantly less residual laxity was found after posterior cruciate ligament reconstruction (PCLR) compared to non-operative management (3.43 vs. 5.47 mm, CI: 1.84-2.23, p < 0.001). Both treatment modalities yielded satisfying functional outcomes and a high return to sports (64-77%, mean: 70.3, CI: 67.8-72.2). Osteoarthritis (OA) occurred less frequently following PCLR (21.5 vs. 44.1%, p < 0.001).

CONCLUSION

In the absence of level I RCTs, this systematic review suggests that surgical management for selected isolated PCL injuries is a reasonable option to consider, especially when the surgeon aims at minimizing residual laxity and presumably secondary osteoarthritis.

LEVEL OF EVIDENCE

IV.

Different injury patterns exist among patients undergoing operative treatment of isolated PCL, combined PCL/ACL, and isolated ACL injuries: a study from the Swedish National Knee Ligament Registry

PURPOSE

To compare demographic characteristics and concomitant injury patterns in patients undergoing primary isolated posterior cruciate ligament reconstruction (PCL-R) and combined posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL) reconstruction (PCL-R/ACL-R) with isolated ACL reconstruction (ACL-R) as a reference using data from the Swedish National Knee Ligament Registry (SNKLR).

METHODS

This cohort study based on the SNKLR comprised patients undergoing either PCL-R, ACL-R, or combined PCL-R/ACL-R between January 1, 2005 and December 31, 2019 in Sweden. Demographic and surgery-related data with regards to injury mechanism, concomitant intraarticular lesions and their treatment, neurovascular damage, and concomitant ligamentous injuries were extracted. Exclusion criteria included concomitant fractures of the femur, fibula, patella or tibia, and quadriceps or patellar tendon injury.

RESULTS

A total of 45,564 patients were included in this study. Isolated PCL-R, combined PCL-R/ACL-R, and isolated ACL-R were performed in 192 (0.4%), 203 (0.5%) and 45,169 (99.1%) patients, respectively. Sports were identified as the cause of 64% of PCL-Rs, 54% of PCL-R/ACL-Rs, and 89% of ACL-Rs, while a traffic-related mechanism was identified in 20% of PCL-Rs, 27% of PCL-R/ACL-Rs and 2% of ACL-Rs. Meniscus injury prevalence was 45% in ACL-Rs, 31% in PCL-R/ACL-Rs and 16% in isolated PCL-Rs (p < 0.001). Cartilage injuries were more common in PCL-R (37%) and PCL-R/ACL-R patients (40%) compared to ACL-R patients (26%, p < 0.001). Concomitant knee ligament injury was identified in 28-44% of PCL-R/ACL-R patients. Neurovascular injuries were present in 9% of PCL-R/ACL-Rs, 1% of PCL-Rs, and 0.3% of ACL-Rs (p < 0.001).

CONCLUSION

Differences in injury mechanisms among patient groups confirm that operatively treated PCL tears are frequently caused by both traffic and sports. Cartilage and ligament injuries were more frequent in patients with PCL-R compared to ACL-R. Consequently, combined PCL and ACL tears should raise suspicion for concomitant knee lesions with clinical relevance during the operative treatment of these complex injuries.

LEVEL OF EVIDENCE

III.

Graft position at the femoral condyle affects knee mobility after posterior cruciate ligament replacement

BACKGROUND

In some cases posterior cruciate ligament (PCL) tears require surgical reconstruction. As the femoral footprint of the ligament is quite large, an ideal graft fixation position on the medial notch wall has not yet been identified. The aim of this study was to compare three different graft fixation positions within the anatomical footprint of the PCL and test it for posterior tibial translation at different knee flexion angles.

METHODS

In six human knee specimens a drawer test was simulated on a material testing machine by applying load on the tibia. At three different knee flexion angles (0°, 45°, 90°) knee mobility was examined with respect to tibial posterior translation and stiffness for the following conditions: intact ligaments, detached PCL, three different graft fixation positions on the femoral condyle.

RESULTS

Replacement of the PCL within its femoral footprint restored knee stability in terms of tibial posterior translation. Low graft position showed comparable drawer displacements to the intact condition for all knee flexion angles (p > 0.344). A higher graft position excessively reduced the posterior translation (p < 0.047) and resulted in a restricted knee mobility and a stiffer joint.

CONCLUSIONS

Graft fixation positions on the femoral condyle play a crucial role in post-operative knee mobility and joint functionality after PCL replacement. Even though all graft fixation positions were placed within the femoral footprint of a native PCL, only the lower position on the medial notch wall showed comparable posterior tibial translation to an intact PCL.

[Comparative study on effectiveness of posterior-posterior triangulation technique and anteroposterior approach for arthroscopic posterior cruciate ligament reconstruction]

Objective

To investigate the effectiveness of the posterior-posterior triangulation technique for arthroscopic posterior cruciate ligament (PCL) reconstruction by comparing with the anteroposterior approach.

Methods

Retrospective analysis was performed on 40 patients who underwent arthroscopic PCL reconstruction between February 2016 and February 2020. The PCLs were reconstructed via anteroposterior approach in 20 patients (anteroposterior approach group) and posterior-posterior triangulation technique in 20 patients (posterior-posterior triangulation technique group). There was no significant difference in gender, age, cause of injury, injury side, disease duration, preoperative International Knee Documentary Committee (IKDC) score, and Lysholm score between the two groups ( P>0.05). The operation time, surgical complications, and postoperative posterior drawer test, Lysholm score, and IKDC score were recorded and compared between the two groups.

Results

The operation time was (65.25±10.05) minutes in the anteroposterior approach group and (56.15±8.15) minutes in the posterior-posterior triangulation technique group, and the difference was significant ( t=3.145, P=0.003). All incisions healed by first intention, and there was no complication such as vascular and nerve injuries or infection. Patients were followed up (27.05±11.95) months in the anteroposterior approach group and (21.40±7.82) months in the posterior-posterior triangulation technique group, with no significant difference ( t=1.770, P=0.085). At last follow-up, the posterior drawer tests were positive in 4 cases (3 cases of stageⅠand 1 case of stage Ⅱ) of the anteroposterior approach group and in 1 case (stageⅠ) of the posterior-posterior triangulation technique group, showing no significant difference between the two groups ( P=0.342). At last follow-up, Lysholm score and IKDC score in both groups were significantly higher than those before operation ( P<0.05). The above functional scores in the posterior-posterior triangulation technique group were significantly higher than those in the anteroposterior approach group ( P<0.05). Imaging reexamination showed that the position, shape, and tension of the grafts were well in both groups, and the grafts were covered with the synovium in the posterior-posterior triangulation technique group, the meniscofemoral ligaments were well preserved. There was no re-rupture of the reconstructed ligament during follow-up.

Conclusion

Compared to the anteroposterior approach, the posterior-posterior triangulation technique provides a clearer view under arthroscopy, no blind spot, sufficient operating space, and relative safety. Moreover, it is easier to retain the remnant and the meniscofemoral ligaments, and can obtain good short-term effectiveness.