A review of the anatomical, biomechanical and kinematic findings of posterior cruciate ligament injury with respect to non-operative management

Why do patients with isolated PCL rupture experience no subjective knee joint instability during walking? An in vivo biomechanical study

Objective

The aim of this study is to assess the kinematic changes in the knee joint during walking in patients with isolated PCL-deficiency (PCLD) to determine the presence of walking-related joint instability (mechanical instability-abnormal displacement form structural damage). Additionally, the study seeks to provide biomechanical insights into the observed differences between subjective and objective assessments.

Methods

35 healthy volunteers and 27 patients with isolated PCLD (both involved and uninvolved sides) were included in the study. All participants walked on a treadmill at a self-selected comfortable speed. An optical 3D motion capture system was employed to collect six degrees of freedom kinematic data of the knee joint during walking. Statistical Parametric Mapping (SPM) was employed, using independent and paired t-tests to evaluate differences between the healthy control group and the PCLD group, as well as between the involved and uninvolved sides, respectively.

Results

Compared with the healthy control group, posterior tibial displacement (the main indicator for anterior-posterior instability) of the involved limb was significantly decreased during 79%-94%. additionally, knee flexion angles of the involved limb were significantly increased compared with healthy control group during 0%-5% and 95%-99% of the gait cycle and significantly decreased during 66%-87%; In the uninvolved side, adaptive gait changes were observed, with knee flexion angles significantly reduced during 20%-50% and 64%-89% of the gait cycle and posterior tibial displacement significantly reduced during 60%-94% compared with the healthy control group; Compared to the uninvolved limb, the involved limb showed increased internal rotation during 62%-71% of the gait cycle and increased knee flexion during 8%-53%, with no significant differences in other dimensions.

Conclusion

From a biomechanical perspective, patients with PCL rupture exhibit no joint instability during walking. Compared to the healthy control group, the involved leg shows a significant reduction in posterior tibial displacement and a diminished range of knee flexion. Clinical evaluations of PCLD should incorporate dynamic functional assessments, thereby providing a more comprehensive basis for treatment decisions.

Influence of Posterior Cruciate Ligament Resection on Knee Balancing and Bone Resection Thickness in Patients Undergoing Robotic-Assisted Total Knee Arthroplasty: A Prospective Study

Introduction The decision to retain or sacrifice the posterior cruciate ligament (PCL) during total knee arthroplasty (TKA) is debated among surgeons. This study aimed to determine the effects of PCL removal on gap balancing, bone-cut thickness, and component positioning. Methods This prospective study included 70 consecutive patients with varus deformity undergoing Mako (Stryker Orthopaedics, Fort Lauderdale, FL, USA) robot-assisted TKA between January 2022 and June 2022. Flexion and extension gaps were initially captured with the PCL intact, using the mechanical alignment start-point, after which the knees were balanced using the functional alignment philosophy. Following this, the PCL was sacrificed, and gaps were recaptured to assess the dynamic change in balance and bone cut thickness, with statistical analyses performed. Results The mean age of the population was 59.46 years (SD = 9.2), with a female preponderance (N = 50, or 71.40%). PCL resection significantly increased the mean flexion gap in the medial compartment from 15.7 mm (SD = 2.36) to 18.8 mm (SD = 1.83), and in the lateral compartment from 22.7 mm (SD = 1.66) to 24.5 mm (SD = 1.62), with minimal change in the extension gap. Rebalancing after PCL resection resulted in a reduction in posterior femoral bone resection thickness, with the posteromedial cut decreasing from 9.6 mm to 7.1 mm, and the posterolateral cut from 4.8 mm to 2.7 mm. Conclusion This study demonstrates that PCL resection consistently leads to a preferential increase in the flexion gap, with minimal impact on the extension gap. The flexion gap increased more significantly in the medial compartment than in the lateral compartment, in approximately a 3:2 proportion. Additionally, PCL resection was associated with decreased posterior femoral bone resection thickness and a trend toward reduced femoral component external rotation.

Management of pediatric posterior cruciate ligament avulsion fractures: a systematic review

PURPOSE

Both open and arthroscopic surgical techniques have been used for PCL avulsion fractures. The goal of this study is to evaluate the effectiveness and safety of the different management strategies proposed for PCL avulsion fractures in children.

METHODS

A systematic literature review was performed utilizing Medline, Scopus, and EMBASE databases from 1977 to the present. PRISMA guidelines were followed. Data were selected and extracted by two independent reviewers. Inclusion criteria were clinical studies reporting injuries in pediatric patients with PCL avulsion injuries. Exclusion criteria were combined PCL and ACL injuries and ligamentous injuries requiring reconstruction. A subgroup analysis was performed between open reduction and arthroscopic surgeries.

FINDINGS/RESULTS

Twenty-six studies were included in this systematic review. Patient sex was reported in 39 patients with a higher number of males (32/39). The age range was 7-18 years old. In the open group, 30/31 patients had clinical improvement or returned to pre-injury activity level with two complications. Lysholm scores ranged from 66 to 99. In the arthroscopic group, 11/12 patients experienced clinical improvement or returned to normal activity levels with only one complication. Lysholm scores ranged from 90 to 100 with a mean of 95. In the non-operative group, 3/3 recovered with evidence of fracture healing, full or near full knee range of motion. One Lysholm score was reported 14 months after injury and was 100/100.

CONCLUSIONS

Open reduction and arthroscopic surgeries are effective and safe treatment options for pediatric PCL avulsion fractures-97% of open reduction and 92% of arthroscopic patients significantly improved symptoms. The complication rates for the open and arthroscopic groups were 11 and 9%, respectively. All three non-operative made full or near full recovery of pre-injury knee status.

LEVEL OF EVIDENCE IV

Systematic review of Level-II-IV studies. Prospero Registration No CRD42021290899.

Activity-Dependent Compensation at the Hip and Ankle at 8 Years After the Reconstruction of Isolated and Combined Posterior Cruciate Ligament Injuries

BACKGROUND

After posterior cruciate ligament reconstruction (PCLR), functional deficits at the knee can persist. It remains unclear if neighboring joints compensate for the knee during demanding activities of daily living.

PURPOSE

To assess long-term alterations in lower limb mechanics in patients after PCLR.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 28 patients who had undergone single-bundle unilateral isolated or combined PCLR performed stair navigation, squat, sit-to-stand, and stand-to-sit tasks at 8.2 ± 2.2 years after surgery. Motion capture and force plates were used to collect kinematic and kinetic data. Then, 3-dimensional hip, knee, and ankle kinematic data of the reconstructed limb were compared with those of the contralateral limb using statistical parametric mapping.

RESULTS

Side-to-side differences at the knee were primarily found during upward-driven movements at 8 years after surgery. The reconstructed knee exhibited lower internal rotation during the initial loading phase of stair ascent versus the contralateral knee (P = .005). During the sit-to-stand task, higher flexion angles during the midcycle (P = .017) and lower external rotation angles (P = .049) were found in the reconstructed knee; sagittal knee (P = .001) and hip (P = .016) moments were lower in the reconstructed limb than the contralateral limb. In downward-driven movements, side-to-side differences were minimal at the knee but prominent at the ankle and hip: during stair descent, the reconstructed ankle exhibited lower dorsiflexion and lower external rotation during the midcycle versus the contralateral ankle (P = .006 and P = .040, respectively). Frontal hip moments in the reconstructed limb were higher than those in the contralateral limb during the stand-to-sit task (P = .010); during squats, sagittal hip angles in the reconstructed limb were higher than those in the contralateral limb (P < .001).

CONCLUSION

Patients after PCLR exhibited compensations at the hip and ankle during downward-driven movements, such as stair descent, squats, and stand-to-sit. Conversely, residual long-term side-to-side differences at the knee were detected during upward-driven movements such as stair ascent and sit-to-stand.

CLINICAL RELEVANCE

After PCLR, side-to-side differences in biomechanical function were activity-dependent and occurred either at the knee or neighboring joints. When referring to the contralateral limb to assess knee function in the reconstructed limb, concentric, upward-driven movements should be prioritized. Compensations at the hip and ankle during downward-driven movements lead to biases in long-term functional assessments.

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.

A method of feature fusion and dimension reduction for knee joint pathology screening and separability evaluation criteria

BACKGROUND AND OBJECTIVE

Knee-joint vibroarthrographic (VAG) signal is an effective method for performing a non-invasive knee osteoarthritis (KOA) diagnosis, VAG signal analysis plays a crucial role in achieving the early pathological screening of the knee joint. In order to improve the accuracy of knee pathology screening and to investigate the method suitable for embedded in wearable diagnostic device for knee joint, this paper proposes a knee pathology screening method. Aiming to fill the gap of lacking suitable and unified evaluation indexes for single feature and fusion feature, this paper proposes feature separability evaluation criteria.

METHODS

In this paper, we propose a knee joint pathology screening method based on feature fusion and dimension reduction combined with random forest classifier, as well as, the evaluation criteria of feature separability. As for pathological screening method, this paper proposes the idea of multi-dimensional feature fusion, using principal component analysis (PCA) to reduce the redundant part of fusion feature (F-F) to obtain deep fusion feature (D-F-F) with more separability. Meanwhile, this paper proposes the maximal information coefficient (MIC) and correlation matrix collinearity (CMC) feature evaluation criteria, these not only can be used as new feature quantitative metrics, but also illustrate that the divisibility of the deep fusion feature is more potent than that before feature dimension reduction.

RESULTS

The experimental results show that the method in this paper has good performance in pathology classification on random forest classifier with 96% accuracy, especially the accuracy of SVM and K-NN are also improved after feature dimension reduction.

CONCLUSION

The results indicate that this classification research has high screening efficiency for KOA diagnosis and could provide a feasible method for computer-assisted non-invasive diagnosis of KOA. And we provide a novel way for separability evaluation of VAG signal features.

Variations in common operations in athletes and non-Athletes

Background

Achieving pre-injury activity level after an injury is the fundamental goal of any orthopedic treatment for an athlete. Unfortunately, pre-injury activity levels differ significantly in different patient categories, especially in athletes and non-athlete. Hence, an outcome suitable to a non-athlete may not be adequate for an athlete. This has led to variations in the surgical approach to the same injury in an athlete and non-athlete.There is plenty of literature published comparing the outcome in athletes and non-athletes after a particular surgery. Scattered discussion about variations in these surgeries based on functional demand was done in many publications. But there was a lack of a comprehensive narrative review summarizing variations in common operations among athletes and non-athletes.

Aim

This review attempted to summarize variations in common sports operations between high functional demand patients and low demand patients and discuss the variations from the author's perspective.

Methods

A review of all the relevant papers were conducted focusing on athletes and non-athletes. Most commonly performed sports surgeries were ACL reconstruction, Meniscal repair, PCL reconstruction, and Shoulder instability surgery. A literature search was done for each commonly performed surgery using relevant keywords in PubMed and Google Scholars. Summary of papers pertinent to athletes and non-athletes were compiled to prepare this narrative review.

Results

There is a lack of papers directly comparing results in athletes and non-athletes. However, many research papers discussed surgical variations in athletes (high demand) and non-athletes (low demand) patients. There are controversies in all commonly performed surgeries, and none of the papers gives a definitive guideline on the approach to athletes and non-athlete.

Conclusion

Rather than a common suggestion on surgical variation, an individualized approach would be appropriate to decide on variation in particular surgery in both athletes and non-athletes.

Gait Adaptations at 8 Years After Reconstruction of Unilateral Isolated and Combined Posterior Cruciate Ligament Injuries

BACKGROUND

It remains unclear how posterior cruciate ligament (PCL) reconstruction influences long-term lower extremity joint biomechanics.

PURPOSE

To determine whether patients who underwent PCL reconstruction exhibited long-term alterations in lower limb gait mechanics.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 26 patients underwent gait analyses at 8.2 ± 2.6 years after primary unilateral PCL reconstruction. Sex- and age-matched healthy controls were analyzed for comparison. Gait data were collected using motion capture and force plates. Hip, knee, and ankle angles and moments were compared during initial contact, early stance, and late stance for the reconstructed and uninjured contralateral limbs of patients who underwent PCL reconstruction (PCL group) as well as the limbs of healthy control participants (CON group).

RESULTS

No side-to-side kinematic differences were noted between the reconstructed and contralateral limbs of the PCL group; some trivial differences were noted in knee and hip moments. However, major differences between the PCL and CON groups occurred at the knee. Reconstructed and contralateral limbs of the PCL group exhibited larger knee flexion angles during initial contact (Δ = 7.0° [P < .001] and Δ = 6.9° [P < .001], respectively), early stance (Δ = 5.8° [P = .003] and Δ = 6.7° [P < .001], respectively), and late stance (Δ = 7.9° [P < .001] and Δ = 8.0° [P < .001], respectively) compared with the CON group. During early stance, contralateral limbs of the PCL group displayed larger knee flexion moments (Δ = 0.20 N·m/kg; P = .014) compared with the CON group, and both reconstructed (Δ = 0.05 N·m/kg; P = .027) and contralateral (Δ = 0.07 N·m/kg; P = .001) limbs of the PCL group exhibited larger knee external rotation moments compared with the CON group. During late stance, reconstructed and contralateral limbs of the PCL group exhibited smaller knee extension moments (Δ = 0.24 N·m/kg [P < .001] and Δ = 0.26 N·m/kg [P < .001], respectively) and knee internal rotation moments (Δ = 0.06 N·m/kg [P < .001] and Δ = 0.06 N·m/kg [P < .001], respectively) compared with the CON group. No discrepancies were observed at the hip; minimal differences were noted in sagittal-plane ankle mechanics.

CONCLUSION

Patients who underwent PCL reconstruction generally exhibited bilateral gait symmetry at 8 years after surgery. However, they exhibited important biomechanical deviations in both knees compared with healthy controls. These modifications likely reflect adaptive gait strategies to protect the PCL after reconstruction.

CLINICAL RELEVANCE

Long-term follow-up analyses of patients who underwent PCL reconstruction should not use the uninjured contralateral limb as a "healthy" reference, as it also exhibits mechanical differences compared with controls. Results could inform the development of neuromuscular and strength training programs targeting the restoration of knee biomechanics similar to healthy controls to prevent early-onset degeneration that is frequently associated with altered biomechanics.

Isolated Partial Femoral Avulsion Fracture of the Posterior Cruciate Ligament in Adults

Objective

To investigate the manifestation, mechanisms, and treatment of isolated partial femoral avulsion fractures of the posterior cruciate ligament (PCL) in adults.

Methods

From January 2011 to December 2018, we retrospectively reviewed the clinical data of three patients with isolated partial femoral avulsion fractures of the PCL who were admitted to our institution. All of these patients were admitted to our emergency department within 24 h after injury. After physical examination and radiographs were taken and reviewed, all patients were admitted and underwent surgical treatment. In a 26‐year‐old man who underwent arthroscopic surgery through the traditional medial and lateral approach before finally converting to open surgery with the posterior approach, the fragment that was finally removed was partially attached to the PCL. In the other two patients, women aged 63 and 68 years, who underwent arthroscopic surgery via the traditional medial and lateral approach, the fragments were large and attached to most fibers of the PCL. We fixed the fragments using hollow screws in arthroscopic view. In addition, in the 63‐year‐old patient, an anchor was embedded to restore the tension of the PCL. Four weeks after surgery, the patients started to wear long leg braces in full extension with the tibia blocked up by cushion. Physical examinations were conducted and radiographs were taken preoperatively and at 4 weeks and 3 months after surgery to evaluate the condition of the injury. The range of motion and the Lysholm knee scoring scale for the knee joint were compared before and after the surgery.

Results

For the three patients, the radiographs taken at 3 months postoperatively showed that the fixation of the screws did not fail, and the subchondral bone was generally normal compared to the preoperative radiographs. CT scanning at 3 months after surgery showed that the fracture healed in the original position of the avulsion site. For all patients, the affected knees presented as stable at physical examination 3 months after surgery; the Lachmann test and the anterior drawer test results were negative. In addition, the flexion–extension, internal rotation, and external rotation were approximately 0°–130°, 0°–30°, and 0°–40° in the 26‐year‐old patient, respectively. The flexion–extension, internal rotation, and external rotation were approximately 0°–100°, 0°–20°, and 0°–35° for the 63‐year‐old patient, respectively. The flexion–extension, internal rotation, and external rotation were approximately 0°–100°, 0°–15°, and 0°–20° for the 68‐year‐old patient, respectively. There was no pain or only little pain 3 months after surgery. There was no swelling or discomfort at the 3‐month follow up. The Lysholm knee scores of the 68‐year‐old, 63‐year‐old, and 26‐year‐old patient were 80, 87, and 95 at 3 months after surgery, respectively, which were obviously improved postoperatively.

Conclusion

The manifestation of isolated partial femoral avulsion fractures of the PCL in adults is often related to the injury mechanism, and surgery is essential for the treatment of these patients. Most of these fractures can be repaired by arthroscopic surgery, but some have to be treated by open surgery.

The amount of displacement can determine non-operative treatment in posterior cruciate ligament avulsion fracture

PURPOSE

It is generally agreed that surgical treatment is warranted for acute posterior cruciate ligament (PCL) avulsion fracture with displacement. However, the amount of displacement that warrants surgical treatment has not been defined. The purpose of this study was to determine the optimal cut-off value for displacement of posterior cruciate ligament avulsion fracture in determining non-operative treatment and to compare the results of non-operative treatment in acute isolated PCL avulsion fractures with non-operative treatment of acute PCL injury.

METHODS

Between 2007 and 2017, 30 consecutive patients with acute isolated PCL avulsion fractures and 70 consecutive patients with acute isolated PCL injuries, all of whom underwent non-operative treatment (cast immobilization with > 2 years of follow-up) were retrospectively analyzed. Clinical scores including the International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity score, as well as side-to-side differences on stress radiographs, were compared between the PCL avulsion fracture and PCL injury groups at the final follow-up. The failure rates of non-operative treatment were also compared. The predictive value of the amount of fracture displacement for successful non-operative treatment was calculated using area under the receiver operating characteristic curve (AUROC). The optimal cut-off of the amount of fracture displacement to determine non-operative treatment was based on the maximal sum of sensitivity and specificity.

RESULTS

The two groups exhibited comparable clinical scores and mean side-to-side differences on stress radiographs. There were 5 (16.6%) failures of non-operative treatment in the PCL avulsion fracture group and 19 (27.1%) failures in the PCL injury group. (n.s) There was a significant positive correlation between the amount of initial avulsion fracture displacement and side-to-side difference in posterior stress radiographs at final follow up (P < 0.001). The optimal cut-off value for the amount of fracture displacement in PCL avulsion fracture to predict failure of non-operative treatment was 6.7 mm (AUROC = 1.0).

CONCLUSION

The outcomes of non-operative treatment of acute isolated PCL avulsion fractures were comparable to those of patients with acute isolated PCL injuries. Acute PCL avulsion injuries with displacement of less than 6.7 mm should be considered for non-operative treatment.

LEVEL OF EVIDENCE

IV.

Longitudinal changes in location-specific cartilage thickness and T2 relaxation-times after posterior cruciate ligament reconstruction for isolated and multiligament injury

BACKGROUND

Knee cartilage undergoes pathological changes after anterior cruciate ligament rupture. However, little is known about the development and progression of structural pathology after posterior cruciate ligament (PCL) injury. This study aimed to determine the location-specific longitudinal changes in knee cartilage morphology (thickness) and composition (T2 relaxation-times) after PCL rupture and reconstruction (PCLR) and compare these to uninjured controls.

METHODS

Fifteen adults (mean age 39 years (standard deviation 10), 12 men) with PCLR for isolated and multiligment injury had MRIs acquired at a minimum 5 years post-PCLR and 1 year later. Location-specific changes in knee cartilage thickness and T2 relaxation-times were determined quantitatively after segmentation, and compared with annualised cartilage changes in 13 active controls (mean age 45 years (standard deviation 4), 6 men).

FINDINGS

Following PCLR, the annual loss of cartilage thickness was greatest in the medial femoral condyle (mean -4.0%, 95% confidence interval [95% CI] -6.7, -1.4), medial tibia (mean -3.7%, 95% CI -6.1, -1.3), and patella (mean -3.2%, 95% CI -4.7, -1.6). In the medial femoral condyle and trochlea, the PCLR group lost significantly more cartilage thickness than uninjured controls (mean difference -3.7%, 95% CI -0.9, -6.5; and -1.8%, 95% CI -0.1, -3.6, respectively). Deep and superficial zone T2 relaxation-times were relatively constant over time, without longitudinal differences between PCLR and control knees.

INTERPRETATION

PCL reconstructed knees displayed substantially greater rates of cartilage loss in the medial tibiofemoral and patellofemoral compartments compared to uninjured controls, highlighting that the process of degeneration remains active many years after injury.

Biomechanical evaluation of PCL reconstruction with suture augmentation

PURPOSE

The purpose of this study was to compare kinematics and patellofemoral contact pressures of all inside and transtibial single bundle PCL reconstructions and determine if suture augmentation further improves the biomechanics of either technique.

METHODS

Cadaveric knees were tested with a posterior drawer force, and varus, valgus, internal and external moments at 30, 60, 90, and 120° of flexion. Displacement, rotation, and patellofemoral contact pressures were compared between: Intact, PCL-deficient, All-Inside PCL reconstruction with (AI-SA) and without (AI) suture augmentation, and transtibial PCL reconstruction with (TT-SA) and without (TT) suture augmentation.

RESULTS

Sectioning the PCL increased posterior tibial translation (PTT) from intact at 60° to 120° of flexion, p < 0.001. AI PCL reconstruction improved stability from the deficient-state but had greater PTT than intact at 90° of flexion, p < 0.05. Adding suture augmentation to the AI reconstruction further reduced PTT to levels that were not statistically different from intact at all flexion angles. TT reconstructed knees had greater PTT than intact knees at 60, 90, and 120° of flexion, p < 0.01. Adding suture augmentation (TT-SA) improved posterior stability to PTT levels that were not statistically different from intact knees at 30, 60, and 120° of flexion. Patellofemoral pressures were highest in PCL-deficient knees at increased angles of flexion and were reduced after reconstruction, but this was not significant.

CONCLUSION

In this time-zero study, both the all-inside and transtibial single bundle PCL reconstructions effectively reduce posterior translation from the deficient-PCL state. In addition, suture augmentation of both techniques provided further anterior-posterior stability.

Posterior cruciate ligament reconstruction implemented by the Ligament Advanced Reinforcement System over a minimum follow-up of 10 years

PURPOSE

This study evaluated the long-term clinical follow-up results of patients who underwent double-bundle posterior cruciate ligament (PCL) reconstruction using the Ligament Advanced Reinforcement System (LARS).

METHODS

Patients were assessed using clinical scores that included the Tegner activity level scale, the Lysholm score, and the International Knee Documentation Committee (IKDC) score. KT-1000 was adopted to assess stability. Radiographs and magnetic resonance imaging (MRI) were used to evaluate osteoarthritis and LARS condition.

RESULTS

This study examined 38 patients, of which follow-up procedures were completed for 33 patients, resulting in a follow-up rate of 86.8%. The average follow-up period was 11.9 ± 1.2 years (range: 10.3-14.2 years). The median scores of the clinical scales were as follows: Tegner activity score, 6 (range: five to seven); Lysholm score, 90 (range: 67-100); and IKDC score, 89.7 (range: 46-100). The median of the side-to-side difference (SSD) was four millimeters (range: 0-10 mm). In radiographs, the moderate OA rate was 6.9%. MRI results revealed that 26 patients exhibited ingrowth and 11 patients exhibited partial rupture of the LARS. With SSD ≤ 3 mm set as the standard for successful knee stabilization, the optimal cutoff point of LARS midsubstance thickness in the receiver operating characteristic (ROC) curve analysis was 14.3 mm.

CONCLUSIONS

Long-term follow-up of the studied patients demonstrated the durability of LARS. However, clinical outcomes showed no enhancement using LARS, so it is not recommended for routine use in PCL reconstruction.

LEVEL OF EVIDENCE

IV.

In vivo static and dynamic lengthening measurements of the posterior cruciate ligament at high knee flexion angles

PURPOSE

Rehabilitation is an important aspect of both non-operative and operative treatments of knee ligament tear. Posterior cruciate ligament (PCL) non-operative treatment consists of a step-by-step rehabilitation protocol and is well described. It goes from rest (phase I) to strengthening exercises (phase IV). More specific and high-intensity exercises such as cutting, sidestepping or jumps are, however, not described in detail, as no in vivo data exist to tell how these exercises constrain the ligaments and whether they have the same effect on all of them, in particular regarding lengthening. The goal of this study was to measure the ligament lengthening in static knee flexion based on 3D reconstructions from magnetic resonance imaging (MRI) and from motion capture and ligament simulation during dynamic exercises.

METHODS

The knee of nine volunteers was first imaged in a closed-bore MRI scanner at various static knee flexion angles (up to 110°), and the corresponding lengthening of the PCL and the other major knee ligaments was measured. Then, the volunteers underwent motion capture of the knee where dynamic exercises (sitting, jumping, sidestepping, etc.) were recorded. For each exercise, knee ligament elongation was simulated and evaluated.

RESULTS

According to the MRI scans, maximal lengthening occurred at 110° of flexion in the anterior cruciate ligament and 90° of flexion in the PCL. Daily living movements such as sitting were predicted to elongate the cruciate ligaments, whereas they shortened the collateral ligaments. More active movements such as jumping put the most constrain to cruciate ligaments.

CONCLUSION

This study provides interesting insights into a tailored postoperative regimen. In particular, knowing the knee ligament lengthening during dynamic exercises can help better define the last stages of the rehabilitation protocol, and hence provide a safe return to play.

Return to Sports and Clinical Outcomes After Arthroscopic Anatomic Posterior Cruciate Ligament Reconstruction With Remnant Preservation

PURPOSE

To evaluate the clinical outcomes of transtibial posterior cruciate ligament reconstruction (PCLR) with remnant preservation in highly active patients and to investigate the rate of return to sports (RTS), quality of sports activities, and patient satisfaction.

METHODS

Patients with a Tegner activity scale of >5 who underwent isolated PCLR from 2013 to 2016 with minimum 2-year follow-up were retrospectively reviewed. Single-bundle PCLR was performed using fresh frozen allograft irradiated with 50 kGy. Subjective assessments included the Lysholm score, subjective International Knee Documentation Committee score, and Tegner activity scale. A questionnaire elicited information associated with RTS and satisfaction. Functional tests included isokinetic muscle strength and single-leg hop tests.

RESULTS

We evaluated 52 patients, with a mean (± standard deviation) follow-up duration of 29.5 ± 8.6 months. The subjective assessments and functional tests significantly improved postoperatively (all P < .001). Mean time to return to full sports activity was 9.7 ± 5.1 months. Thirty-eight (73.1%) and 45 (86.5%) patients could return to previous sports activities at 9 and 24 months, respectively. A sports-experience questionnaire indicated that 48% and 69.2% of the patients were participating with unlimited effort and performance, respectively, and no pain at 9 and 24 months. Multivariate analysis indicated that extensor deficit (odds ratio [OR] 4.2, 95% confidence interval [CI] 1.342 to 17.839), flexor deficit at 60°/s (OR 3.8, 95% CI 1.081 to 14.476), Limb Symmetry Index (%) for the single-leg vertical jump test (OR 2.2, 95% CI 1.212 to 9.227), and satisfaction (OR 2.8, 95% CI 1.186 to 10.281) were significantly associated with failure of not returning to preinjury sports activity levels at the 9-month follow-up.

CONCLUSIONS

Arthroscopic anatomic PCLR with remnant preservation showed high rates of RTS and high patient satisfaction, as well as satisfactory clinical results in highly active patients. This surgical technique could be an effective treatment for grade III posterior cruciate ligament injury in highly active patients.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Variation in Graft Bending Angle During Range of Motion in Single-Bundle Posterior Cruciate Ligament Reconstruction: A 3-Dimensional Computed Tomography Analysis of 2 Techniques

PURPOSE

To compare variations in femoral graft bending angle during range of motion (ROM) of the knee between inside-out (IO) and retro-socket outside-in (OI) techniques in posterior cruciate ligament (PCL) reconstruction using in vivo 3-dimensional (3D) computed tomography analysis.

METHODS

Ten patients underwent PCL reconstruction by the IO technique (5 patients) or the retro-socket OI technique (5 patients) for suspensory femoral fixation. After PCL reconstruction, 3D computed tomography was performed in 0° extension and 90° flexion to reconstruct 3D femur and tibia bone models using Mimics software. Positions of femur and tibia at 30°, 45°, and 60° flexion were reproduced by determining the kinematic factors of anteroposterior translation, mediolateral translation, and internal-external rotation angle of each patient based on previously measured kinematic data. Variation in graft bending angle according to the flexion range of the knee was calculated by the difference in graft angulation measured at each flexion angle. The results were compared between the 2 techniques.

RESULTS

There was significant difference in variation of femoral graft bending angle between IO and retro-socket OI techniques from 0° to 90° flexion of the knee (P = .008). Significant difference was also noticed at 30° to 45° (P = .008), 45° to 60° (P = .008), and 60° to 90° (P = .016) ROM of the knee between the 2 groups.

CONCLUSIONS

The retro-socket OI technique resulted in less variation in femoral graft bending angle compared with the IO technique during knee ROM. We recommend the retro-socket OI technique for femoral tunnel placement to reduce the graft motion at the intra-articular femoral tunnel aperture.

CLINICAL RELEVANCE

The retro-socket OI technique produces significantly less variation in femoral graft bending angle when compared with the IO technique. Such reduction in variation of femoral graft bending angle might be related to lower stress at the femoral tunnel aperture.

Electromyography-Driven Forward Dynamics Simulation to Estimate In Vivo Joint Contact Forces During Normal, Smooth, and Bouncy Gaits

Computational models that predict in vivo joint loading and muscle forces can potentially enhance and augment our knowledge of both typical and pathological gaits. To adopt such models into clinical applications, studies validating modeling predictions are essential. This study created a full-body musculoskeletal model using data from the "Sixth Grand Challenge Competition to Predict in vivo Knee Loads." This model incorporates subject-specific geometries of the right leg in order to concurrently predict knee contact forces, ligament forces, muscle forces, and ground contact forces. The objectives of this paper are twofold: (1) to describe an electromyography (EMG)-driven modeling methodology to predict knee contact forces and (2) to validate model predictions by evaluating the model predictions against known values for a patient with an instrumented total knee replacement (TKR) for three distinctly different gait styles (normal, smooth, and bouncy gaits). The model integrates a subject-specific knee model onto a previously validated generic full-body musculoskeletal model. The combined model included six degrees-of-freedom (6DOF) patellofemoral and tibiofemoral joints, ligament forces, and deformable contact forces with viscous damping. The foot/shoe/floor interactions were modeled by incorporating shoe geometries to the feet. Contact between shoe segments and the floor surface was used to constrain the shoe segments. A novel EMG-driven feedforward with feedback trim motor control strategy was used to concurrently estimate muscle forces and knee contact forces from standard motion capture data collected on the individual subject. The predicted medial, lateral, and total tibiofemoral forces represented the overall measured magnitude and temporal patterns with good root-mean-squared errors (RMSEs) and Pearson's correlation (p2). The model accuracy was high: medial, lateral, and total tibiofemoral contact force RMSEs = 0.15, 0.14, 0.21 body weight (BW), and (0.92 < p2 < 0.96) for normal gait; RMSEs = 0.18 BW, 0.21 BW, 0.29 BW, and (0.81 < p2 < 0.93) for smooth gait; and RMSEs = 0.21 BW, 0.22 BW, 0.33 BW, and (0.86 < p2 < 0.95) for bouncy gait, respectively. Overall, the model captured the general shape, magnitude, and temporal patterns of the contact force profiles accurately. Potential applications of this proposed model include predictive biomechanics simulations, design of TKR components, soft tissue balancing, and surgical simulation.

An extended OpenSim knee model for analysis of strains of connective tissues

Background

OpenSim musculoskeletal models provide an accurate simulation environment that eases limitations of in vivo and in vitro studies. In this work, a biomechanical knee model was formulated with femoral articular cartilages and menisci along with 25 connective tissue bundles representing ligaments and capsules. The strain patterns of the connective tissues in the presence of femoral articular cartilage and menisci in the OpenSim knee model was probed in a first of its kind study.

Methods

The effect of knee flexion (0°–120°), knee rotation (− 40° to 30°) and knee adduction (− 15° to 15°) on the anterior cruciate, posterior cruciate, medial collateral, lateral collateral ligaments and other connective tissues were studied by passive simulation. Further, a new parameter for assessment of strain namely, the differential inter-bundle strain of the connective tissues were analyzed to provide new insights for injury kinematics.

Results

ACL, PCL, LCL and PL was observed to follow a parabolic strain pattern during flexion while MCL represented linear strain patterns. All connective tissues showed non-symmetric parabolic strain variation during rotation. During adduction, the strain variation was linear for the knee bundles except for FL, PFL and TL.

Conclusions

Strains higher than 0.1 were observed in most of the bundles during lateral rotation followed by abduction, medial rotation and adduction. In the case of flexion, highest strains were observed in aACL and aPCL. A combination of strains at a flexion of 0° with medial rotation of 30° or a flexion of 80° with rotation of 30° are evaluated as rupture-prone kinematics.

Electronic supplementary material

The online version of this article (10.1186/s12938-018-0474-8) contains supplementary material, which is available to authorized users.

Successful return to sports in athletes following non-operative management of acute isolated posterior cruciate ligament injuries

Aims

The aim of this study was to report the outcome of the non-operative treatment of high-grade posterior cruciate ligament (PCL) injuries, particularly Hughston grade III injuries, which have not previously been described.

Patients and Methods

This was a prospective study involving 46 consecutive patients who were athletes with MRI-confirmed isolated PCL injuries presenting within four weeks of injury. All had Hughston grade II (25 athletes) or III (21 athletes) injuries. Our non-operative treatment regimen involved initial bracing, followed by an individualised rehabilitation programme determined by the symptoms and physical signs. The patients were reviewed until they had returned to sports-specific training, and were reviewed again at a mean of 5.2 years (3 to 9).

Results

The mean time to return to sports-specific training was 10.6 weeks and the mean time to return to full competitive sport was 16.4 weeks (10 to 40). A total of 42 patients (91.3%) were playing at the same or higher level of sport two years after the injury, with a mean Tegner activity score of 9 (5 to 10). At five years, 32 patients (69.5%) were playing at the same or higher level of sport, and 38 patients (82.6%) were playing at a competitive level, with a mean Tegner activity score of 9 (5 to 10).

Conclusions

Medium-term review of a series of athletes suggests that commencing the non-operative management of isolated, Hughston grade II and III PCL injuries within four weeks of injury gives excellent functional outcomes with a high proportion returning to the same or higher level of sport. Cite this article: Bone Joint J 2017;99-B:774–8.

Isolated posterior cruciate ligament tears: an update of management

Isolated posterior cruciate ligament (PCL) tears are much less frequent than anterior cruciate ligament (ACL) tears.Abrupt posterior tibial translation (such as dashboard impact), falls in hyperflexion and direct hyperextension trauma are the most frequent mechanisms of production.The anterolateral bundle represents two-thirds of PCL mass and is reconstructed in single-bundle techniques.The PCL has an intrinsic capability for healing. This is the reason why, nowadays, the majority of isolated PCL tears are managed non-operatively, with rehabilitation and bracing.Recent studies have focused on double-bundle reconstruction techniques, as they seem to restore knee kinematics.No significant clinical differences have been established between single versus double-bundle techniques, autograft versus allograft, transtibial tunnel versus tibial inlay techniques or remnant-preserving versus remnant-release techniques. Cite this article: EFORT Open Rev 2017;2:89-96. DOI: 10.1302/2058-5241.2.160009.

The biomechanical and histological effects of posterior cruciate ligament rupture on the medial tibial plateau

Background

The objective of this study was to investigate the biomechanical and histological effects of the posterior cruciate ligament (PCL) on the medial tibial plateau.

Methods

A total of 12 cadaveric human knee specimens were collected and grouped as follows: the PCL intact group (n = 12), the anterolateral bundle rupture group (n = 6), the postmedial bundle rupture group (n = 6), and the PCL rupture group (n = 12). The strain on the anterior, middle, and posterior parts of the medial tibial plateau with an axial loading force at different flexion angles was measured and analyzed, respectively. Forty-eight rabbits were chosen for animal study: surgery was performed on the one side of each rabbit randomly (experimental group), while the other side was taken as control (control group). Every 12 rabbits were culled at each of the four selected time points to collect the medial tibial plateau for morphological and histological observation.

Results

The PCL rupture, either partial or complete, may generate an abnormal load on all the parts of the medial tibial plateau with axial loading at all positions. Noticeable time-dependent degenerative histological changes of the medial tibial plateau were observed in the rabbit models of PCL rupture. Compared with the control group, all the PCL rupture groups exhibited a higher expression of the matrix metalloproteinase-7 (MMP-7) and the tissue inhibitors of metalloproteinase-1 (TIMP-1) at all the time points.

Conclusions

Either partial or complete PCL rupture may generate an abnormal load on all the parts of the medial tibial plateau with axial loading at all the positions and may cause cartilage degeneration on the medial tibial plateau.

Arthroscopic fixation of an avulsion fracture of the tibia involving the posterior cruciate ligament

A total of 22 patients with a tibial avulsion fracture involving the insertion of the posterior cruciate ligament (PCL) with grade II or III posterior laxity were reduced and fixed arthroscopically using routine anterior and double posteromedial portals. A double-strand Ethibond suture was inserted into the joint and wrapped around the PCL from anterior to posterior to secure the ligament above the avulsed bony fragment. Two tibial bone tunnels were created using the PCL reconstruction guide, aiming at the medial and lateral borders of the tibial bed. The ends of the suture were pulled out through the bone tunnels and tied over the tibial cortex between the openings of the tunnels to reduce and secure the bony fragment. Satisfactory reduction of the fracture was checked arthroscopically and radiographically.

The patients were followed-up for a mean of 24.5 months (19 to 28). Bone union occurred six weeks post-operatively. At final follow-up, all patients had a negative posterior drawer test and a full range of movement. KT-1000 arthrometer examination showed that the mean post-operative side-to-side difference improved from 10.9 mm (standard deviation (sd) 0.7) pre-operatively to 1.5 mm (sd 0.6) (p = 0.001). The mean Tegner and the International Knee Documentation Committee scores improved significantly (p = 0.001). The mean Lysholm score at final follow-up was 92.0 (85 to 96).

We conclude that this technique is convenient, reliable and minimally invasive and successfully restores the stability and function of the knee.

Cite this article: Bone Joint J 2015;97-B:1220–5.

Posterior cruciate ligament tears in Taiwan: an analysis of 140 surgically treated cases

INTRODUCTION

Posterior cruciate ligament (PCL) tears are commonly due to motor vehicle accidents or sports-related trauma but can differ geographically. We report the various causes, types, and associated injuries of PCL tears in Taiwan.

METHODS

One hundred forty patients with arthroscopically treated PCL tears were reviewed.

RESULTS

Scooter-related trauma was the most common cause of PCL tear in our series and is typically an isolated ligamentous injury. High-velocity motor vehicle accidents accounted for a small percentage of PCL tears.

CONCLUSION

Scooter-related PCL tears are common in Taiwanese patients and are often isolated ligamentous injuries similar to low-velocity sports-related PCL injuries.

Appraising the methodological quality of cadaveric studies: validation of the QUACS scale

Although systematic reviews are conducted in the field of anatomical research, no instruments exist for the assessment of study quality. Thus, our objective was to develop a valid tool that reliably assesses the methodological quality of observational cadaveric studies. The QUACS scale (QUality Appraisal for Cadaveric Studies) was developed using an expert consensus process. It consists of a 13-item checklist addressing the design, conduct and report of cadaveric dissection studies. To evaluate inter-rater reliability, a blinded investigator obtained an initial pool of 120 observational cadaveric studies. Sixty-eight of them were selected randomly according to sample size calculations. Three independent researchers rated each publication by means of the QUACS scale. The reliability of the total score was estimated using the intraclass correlation coefficient (ICC). To assess agreement among individual items, margin-free kappa values were calculated. For construct validity, two experts (an anatomist and an experienced physician) categorized the quality of 15 randomly selected studies as 'excellent' (4 points), 'moderate to good' (3 points), poor to moderate' (2 points) or 'poor' (1 point). Kendall's tau rank correlation was used to compare the expert ratings with the scores on the QUACS scale. An evaluation of feasibility was carried out during the reliability analysis. All three raters recorded the duration of quality appraisal for each article. Means were used to describe average time exposure. The ICC for the total score was 0.87 (95% confidence interval: 0.82-0.92; P < 0.0001). For individual items, margin-free kappa values ranged between 0.56 and 0.96 with an agreement of 69-97% among the three raters. Kendall's tau B coefficient of the association between expert ratings and the results obtained with the QUACS scale was 0.69 (P < 0.01). Required rating time per article was 5.4 ± 1.6 min. The QUACS scale is highly reliable and exhibits strong construct validity. Thus, it can confidently be applied in assessing the methodological quality of observational dissection studies.

Multiple Looping Technique for Tibial Fixation in Posterior Cruciate Ligament Reconstruction of the Knee

The outcomes of posterior cruciate ligament reconstruction may be negatively affected by insufficient tibial tunnel fixation due to relatively lower bone density of the proximal tibia. We introduce a new technique of tibial fixation for posterior cruciate ligament reconstruction using free tendon Achilles allograft that is less affected by the bone density of the tibial metaphysis.

GAIT PATTERNS AFTER POSTERIOR CRUCIATE LIGAMENT INJURY: A COMPARISON OF SYMPTOMATIC AND ASYMPTOMATIC PATIENTS

This study examined chronic, isolated posterior cruciate ligament (PCL) rupture patients, dividing them into symptomatic and asymptomatic groups according to whether they displayed obvious symptoms in daily activities. Each group comprised 10 patients while 10 healthy, young individuals were adopted as the control group. Using a three-dimensional motion analysis system and force plates, the gait patterns of the PCL-deficient patients were analyzed from both kinematics and kinetics perspectives to identify whether they differed from the control group and to compare symmetry between the injured and uninjured sides. The results showed that the symptomatic PCL-deficient group was closer to "normal", and the asymptomatic PCL-deficient group showed less knee extension moment and lower power absorption in the terminal stance than the control group. Additionally, the symptomatic PCL-deficient group appeared to have a relatively symmetric gait while the asymptomatic PCL-deficient group primarily showed an asymmetric gait also occurring in the terminal stance, including less joint moment and lower power absorption of the hip and knee, and lower vertical ground reaction force (GRF). Regarding the gait adaptations of the asymptomatic PCL-deficient group these compensation mechanisms are most likely to have been produced in order to assist in joint stabilization and reduce symptoms in joints.