Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 1: anatomy, biomechanics and diagnostics

Specific fibre areas in the femoral footprint of the posterior cruciate ligament act as a major contributor in resisting posterior tibial displacement: A biomechanical robotic investigation

PURPOSE

Similar to the anterior cruciate ligament, the femoral footprint of the posterior cruciate ligament (PCL) is composed of different fibre areas, possibly having distinct biomechanical functions. The aim of this study was to determine the role of different fibre areas of the femoral footprint of the PCL in restraining posterior tibial translation (PTT).

METHODS

A sequential cutting study was performed on eight fresh-frozen human knee specimens, utilizing a six-degrees-of-freedom robotic test setup. The femoral attachment of the PCL was divided into 15 areas, which were sequentially cut from the bone in a randomized sequence. After determining the native knee kinematics, a displacement-controlled protocol was performed replaying the native motion, while constantly measuring the force. The reduction of the restraining force presented the percentage contribution of each cut, according to the principle of superposition.

RESULTS

The PCL was found to contribute 29 ± 16% in 0°, 51 ± 24% in 30°, 60 ± 22% in 60° and 55 ± 18% in 90°, to restricting a PTT. The fibre areas contributing the most were located at the proximal border of the PCL footprint, away from the cartilage, and directly adjacent to the medial intercondylar ridge (p < 0.05). Of these, one fibre area showed the highest contribution at all flexion angles. This area was located at the posterior half of the medial intercondylar ridge. No clear assignment of the areas to either the anterolateral or posteromedial bundle was possible.

CONCLUSION

An area towards the proximal and posterior part of the femoral PCL footprint was found to significantly restrain a posterior tibial force. Based on the data of this testing setup, a PCL graft positioned at the identified area may best mimic the part of the native PCL, which bears the most load in resisting a PTT force.

LEVEL OF EVIDENCE

No evidence level (laboratory study).

Nonanatomic Posteromedial Bundle Augmentation of the Posterior Cruciate Ligament after Hyperextension Trauma

The surgical management of posterior cruciate ligament (PCL) injuries can be challenging. As most PCL injuries occur in a flexed knee position, the anterolateral bundle is thought to be more commonly injured than the posteromedial bundle (PMB); however, in hyperextension, the PMB plays a more significant role. The smaller size of the PMB compared with the anterolateral bundle and its lower strength may explain why isolated hyperextension PMB injuries can be easily overlooked. In this Technical Note, a surgical technique to perform a nonanatomic PMB augmentation of the PCL using a gracilis tendon autograft or allograft is reported. These technical features aim to overcome current limitations in existing techniques to address the symptoms after partial PCL hyperextension injuries.

Comparative morphology of the cruciate ligaments: A radiological study

Background

The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are important structures to maintain knee stability. The present study aimed to further enrich understandings of the morphology of the cruciate ligaments and explore the relationship between the diameter of ACL and PCL.

Method

This study collected valid MRI samples of 50 male and 50 female normal right knee joints and measured the diameter of each point of the ACL and PCL through the 3D Slicer.

Results

The diameter of the ACL in the sagittal MRI of the normal right knee joint was significantly different from the diameter of each point of the PCL. The average diameter of each point of the ACL was larger than the diameter of the corresponding point of the PCL. Males and females had statistical differences in their PCL origin point, PCL midpoint, ACL origin point, ACL midpoint, and ACL insertion point diameters under sagittal MRI examination. The average diameter of males was greater than the average diameter of females at the above corresponding sites. In sagittal MRI scans of the normal right knee joint, we observed that only the origin point of the PCL exhibited a moderate correlation with the midpoint and insertion point of the ACL in terms of their respective diameters.

Conclusion

The correlation between diameters of normal ACL and PCL in knee joint MRI was moderate and may help clinicians determine appropriate graft for cruciate ligament reconstruction surgery quickly for severe cruciate ligament injuries.

[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.

Surgical approach on combined chronic patellar tendon and bicruciate knee ligament injury

A combined injury of the patellar tendon and both the anterior and posterior cruciate ligaments is disabling. It directly affects knee kinematics and biomechanics, presenting a considerable surgical challenge. In this complex and uncommon injury, decision-making should take into account the surgeon's experience and consider one- or two-stage surgery, tendon graft, graft fixation, and rehabilitation protocol. This manuscript discusses the surgical approach based on a comprehensive understanding of the patellar tendon and bicruciate biomechanics to guide which structures should be reconstructed first, especially when a two-stage procedure is chosen.

Patient Reported Clinical Outcomes Following PCL Suture Augmentation in Patients with Multiligamentous Knee Injury: A Retrospective Observational Study

Purpose

To compare the patient-reported outcomes between patients with posterior cruciate ligament (PCL) reconstruction or repair alone versus PCL reconstruction or repair with internal bracing (IB) in the context of multi-ligament knee injuries (MLKI).

Methods

All patients who underwent surgical management of MLKI at two institutions between 2006 and 2020 were retrospectively identified and offered participation in the study. Patient reported outcomes were measured via three instruments: Lysholm Knee score, Multiligament Quality of Life (ML-QOL), and the Patient-Reported Outcomes Measurement Information System (PROMIS) computer adaptive testing (CAT). The postoperative outcomes and reoperation rates were compared between the internal bracing and non-internal bracing groups.

Results

Fifty-two patients were analyzed; 34 were included in the IB group (17.6% female; age 33.1 ±1.60 years), and 18 were included in the non-IB group (11.1% female; age 34.1 ±3.72 years). Mean follow-up time of the entire cohort was 1.44 ± 0.22 years (IB: 1.21 ± 0.18; non-IB: 2.1 ±0.65). There were no significant differences between PROMIS CAT [PROMIS Pain (54.4 ±1.78 vs 51.7 ±1.70, p=0.319), Physical Function (44.3 ±2.27 vs 47.9 ±1.52, p=0.294), Mobility (44.0 ±1.71 vs 46.1 ±2.10, p=0.463)], ML-QOL [ML-QOL Physical Impairment (40.7 ±4.21 vs 41.7±5.10, p=0.884), Emotional Impairment (49.2 ±4.88 vs 44.7±5.87, p=0.579), Activity Limitation (43.5 ±4.56 vs 31.5±3.62, p=0.087), Societal Involvement (44.9 ±4.96 vs 37.5 ±5.30, p=0.345)] and Lysholm knee score (61.8 ±4.55 vs 61.0 ±4.95, p=0.916) postoperatively compared to the non-IB group.

Conclusion

In this group of patients, function and patient-reported outcomes between patients treated with PCL reconstruction and repair without internal brace versus those with additional internal brace augmentation were not significantly different. Further research encompassing a larger patient sample is necessary to investigate the efficacy of the internal brace for PCL injury in the context of MLKI injuries.

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.

Higher rates of fully preserved posterior cruciate ligament in total knee arthroplasty using a double tibial cut: a prospective randomized controlled trial

PURPOSE

In cruciate retaining total knee arthroplasty, posterior cruciate ligament damage may occur during tibial cutting. A prospective randomized study was conducted to investigate whether a novel tibial cutting technique was more effective than the currently used techniques.

MATERIALS AND METHODS

Patients undergoing cruciate retaining total knee arthroplasty were recruited in a prospective, randomized, controlled trial. In 25 patients (group 1) the tibial cut was performed using a double tibial cut technique; in 25 (group 2) and 25 (group 3) patients, the bone island and en bloc resection techniques were performed, respectively. Posterior cruciate ligament integrity and femoral rollback were assessed at the end of surgery. The Oxford Knee Score, WOMAC score and range of motion were assessed postoperatively.

RESULTS

Posterior cruciate ligament was completely preserved in 92% of patients in group 1 and in 64% in group 2 and 3, respectively (p = 0.03). The Oxford Knee Score and WOMAC scores did not differ between groups (p = 0.4). The mean knee flexion was 126.4°, 121.5° and 123.9° in groups 1, 2 and 3, respectively (p = 0.04). The femoral rollback at 120° flexion was 80.7%, 72.2% and 75.4% in groups 1, 2 and 3, respectively (p = 0.01).

CONCLUSIONS

The double cut technique preserves the posterior cruciate ligament at significantly higher rates than the bone island or en bloc resection techniques. Better posterior cruciate ligament preservation may improve the femoral rollback and knee flexion.

LEVEL OF EVIDENCE

Prospective randomized controlled trial, Level I.

Minimizing the risk of injury to the popliteal artery during pullout repair of medial meniscus posterior root tears: A cadaveric study

Background

The purpose of this study was to investigate the positional effect of guide pins used in the transtibial pullout repair of medial meniscus posterior root tears on the popliteal artery.

Methods

We used eight cadaveric knees. Two 2.4-mm guide pins were inserted into the posterior root of the medial meniscus at 50° to the articular surface from the medial edge of the tibial tuberosity (anteromedial group) and the anterior edge of the medial collateral ligament (posteromedial group) using an aiming guide placed at the posterior root attachment of the medial meniscus from the anteromedial portal. The posterior capsule was dissected, and the popliteal artery was identified. The positional effect of the guide pins on the popliteal artery was photographed arthroscopically at 0°, 30°, 60°, and 90° knee flexion angles. The popliteal artery diameter and the minimum distance between the popliteal artery center and the guide pin tip were measured.

Results

At 90° knee flexion, most of the guide pins in the anteromedial (6 knees; 75 %) and posteromedial groups (7 knees; 87.5 %) collided with the femoral intercondylar wall. The rate of collision was significantly higher at the 90° knee flexion position than that at other angles (p = 0.02). The average shortest distance between the popliteal artery center and the guide pin tip at 0° knee flexion in the posteromedial group (5.4 mm ± 3.4 mm) was significantly greater than that at other knee flexion angles, although the mean distance in the posteromedial group was so negligible that the guide pin could penetrate the popliteal artery.

Conclusions

Knee flexion at 90° causes less damage to the popliteal artery during the transtibial pullout repair of medial meniscus posterior root tears.

Preoperative joint line obliquity, a newly identified factor for overcorrection, can be incorporated into a novel preoperative planning method to optimise alignment in high tibial osteotomy

PURPOSE

The aim of this study was to analyse the factors associated with additional postoperative alignment changes after accurate bony correction by selecting only patients with well-performed bony correction as planned and develop a method of incorporating significant factors into preoperative planning.

METHODS

Among 104 consecutive patients who underwent medial open wedge high tibial osteotomy (MOWHTO) between October 2019 and July 2022, 61 with well-performed bony corrections were retrospectively reviewed. The major criterion for well-performed bony correction was a difference of <1° between the simulated medial proximal tibial angle (MPTA) and the actual postoperative MPTA as measured in three dimensions. Radiographic parameters, such as the joint line convergence angle (JLCA) and joint line obliquity (JLO), were measured preoperatively and postoperatively, utilising standing and supine whole lower extremity anteroposterior, valgus and varus stress radiographs. Multiple linear regression analysis identified the factors affecting alignment changes, and a prediction model was developed. A method for applying this prediction model to preoperative planning was proposed.

RESULTS

Preoperative JLCA on standing (preJLCAstd ), preoperative JLCA on 0° valgus stress radiograph (vgJLCA0 ), and preoperative JLO (preJLO) were significantly correlated with JLCA change (∆JLCA) (p < 0.001, p < 0.001, p = 0.006). The prediction model was estimated as ∆JLCA = 0.493 × (vgJLCA0 ) - 0.727 × (preJLCAstd ) + 0.189 × (preJLO) - 1.587 in. (R = 0.815, modified R2  = 0.646, p < 0.001). The proposed method resulted in a reduced overcorrection rate (p = 0.003) and an improved proportion of acceptable alignments (p = 0.013).

CONCLUSION

PreJLCAstd , vgJLCA0  and preJLO can be used to estimate ∆JLCA. PreJLO was recently identified as a significant factor associated with additional alignment changes. Utilising the proposed preoperative planning and a prediction model with these factors shows promise in calibrating postoperative alignment after MOWHTO.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Platelets-rich-plasma in management of non operative post cruciate ligament injury

Posterior cruciate ligament (PCL) injury is a rare ligamentous knee injury which most commonly occurs due to direct trauma; it represents only 0.65% of knee injuries. On the basis of magnetic resonance imaging (MRI), PCL injury is divided into surgical and non-surgical. In the last few years we have witnessed an increasing interest in regenerative medicine. The use of innovative techniques allow the reduction of rehabilitation times in sports injuries. Platelet-Rich-Plasma (PRP) is a plasma-derived which stimulate the tissue repair. The objective of our work is to compare the rehabilitation times in PCL non-operative injuries treated with standard conservative treatment and PCL injuries treated with autologous PRP followed by rehabilitation program. We divided patients into two different groups: Group A formed by patients who underwent a standard conservative rehabilitation program and Group B which included patients treated by ultrasound guided PRP injection and following physiotherapy program. Both groups of patients resumed sports activities; however the rehabilitation times for patients which had undergone treatment with autologous PRP injection were reduced compared to patients who underwent a standard conservative treatment.

The larger patellar tilt angle and lower intercondylar notch angle might increase posterior cruciate ligament injury risk: a retrospective comparative study

BACKGROUND

Posterior cruciate ligament (PCL) injuries are common ligament injuries of the knee, and previous studies often focused on the associations between the morphology of the knee and PCL injuries. Studies on the correlation between PCL injuries and patellofemoral alignment are limited.

METHODS

This retrospective study included 92 patients with PCL injured and 92 patients with PCL intact. Measurement parameters were compared between the two groups, including patellar tilt angle, congruence angle, patellar height, hip-knee-ankle angle, lateral trochlear inclination, femoral condyle ratio, bicondylar width, intercondylar notch width and index, notch angle, trochlear facet asymmetry, and trochlear sulcus depth and angle. Independent risk factors associated with PCL injuries were identified by logistic regression analyses.

RESULTS

In the PCL injured group, the patellar tilt angle was significantly larger (13.19 ± 5.90° vs. 10.02 ± 4.95°, P = 0.04); the intercondylar notch angle was significantly lower (60.97 ± 7.83° vs. 67.01 ± 6.00°, P = 0.004); the medial and lateral femoral condyle ratio were significantly larger (0.63 ± 0.64 vs. 0.60 ± 0.56, P = 0.031; 0.65 ± 0.60 vs. 0.58 ± 0.53, P = 0.005) than in the PCL intact group. There were 11 patients with patellar dislocation in the PCL injured group, accounting for 12%. In these patients, the patellar height was higher (1.39 ± 0.17 vs. 1.09 ± 0.25, P = 0.009); the trochlear sulcus angle was larger (157.70 ± 8.7° vs. 141.80 ± 8.78°, P < 0.001); and the trochlear sulcus depth was shallower (3.10 ± 1.20mm vs. 5.11 ± 1.48mm, P = 0.003) than those in the patients without patellar dislocation. Multivariate analyses showed that patellar tilt angle (each increase 1 degree, OR = 1.14) and intercondylar notch angle (each increase 1 degree, OR = 0.90) were independent risk factors for PCL injuries.

CONCLUSION

The patients with PCL injuries had larger patellar tilt angles, lower intercondylar notch angles, and longer posterior femoral condyles than patients with PCL intact. The larger patellar tilt angle and lower intercondylar notch angle might be risk factors for PCL injuries.

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.

Smaller intercondylar notch size and smaller ACL volume increase posterior cruciate ligament rupture risk

PURPOSE

Little is known about risk factors for sustaining a posterior cruciate ligament (PCL) rupture. Identifying risk factors is the first step in preventing a PCL rupture from occurring. The morphology of the knee in patients who ruptured their PCL may differ from that of control patients. The hypothesis was that the intercondylar notch dimensions, 3-D volumes of the intercondylar notch and, the 3-D volumes of both the ACL and the PCL were correlated to the presence of a PCL rupture.

METHODS

The magnetic resonance imaging (MRI) scans of 30 patients with a proven PCL rupture were compared to 30 matched control patients with proven intact ACL and PCL. Control patients were selected from patients with knee trauma during sports but without cruciate ligament injury. Patients have been matched for age, height, weight, BMI, and sex. The volumes of the intercondylar notch and both the ACL and PCL were measured on 3D reconstructions. Second, the bicondylar width, the notch width, and the notch width index were measured of all subjects. The relationship between our measurements and the presence of a PCL rupture was analysed.

RESULTS

The results show a significant difference in the volumes of the intercondylar notch and the ACL between patients with a ruptured PCL and control patients. Patients with a PCL rupture have smaller intercondylar notch volumes and smaller ACL volumes. There were no significant differences in the bicondylar width, notch width, and notch width index. In the control patients, a significant correlation between the volume of the PCL and the volume of the ACL was found (0.673, p < 0.001).

CONCLUSION

Patients with a PCL rupture have smaller intercondylar volumes and smaller ACL volumes when compared to control patients. Second, patients with smaller ACL volumes have smaller PCL volumes. This study shows, for the first time, that there are significant size and volume differences in the shape of the knee between patients with a PCL rupture and control patients.

LEVEL OF EVIDENCE

IV.

Different patient and activity-related characteristics result in different injury profiles for patients with anterior cruciate ligament and posterior cruciate ligament injuries

PURPOSE

To compare patient characteristics including patient sex, age, body mass index (BMI), activities at the time of injury and injury profiles in patients with anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries.

METHODS

Data were obtained from the Swedish National Knee Ligament Registry. Two study groups were created: (1) index ACL reconstruction (ACL group) and (2) index PCL reconstruction (PCL group). Between-group differences were investigated using Fisher's exact test and Fisher's non-parametric permutation test for dichotomous variables and continuous variables, respectively.

RESULTS

Of 39,010 patients, 38,904 were ACL injuries. A larger proportion of patients with combined injuries to the PCL, meniscus and cartilage were female, aged > 25 years and with a BMI of > 35 kg/m² compared with patients with combined injuries to the ACL, meniscus and cartilage. An isolated ACL injury was more commonly found in males, while all other injury profiles of ACL, including combined injuries with meniscus, cartilage and collateral ligament injuries, were more frequently observed in females. The PCL injuries were sustained either during pivoting sports, non-pivoting sports or were traffic-related.

CONCLUSION

Different patient characteristics (BMI, age and sex), and activities at the time of injury (sport- versus traffic-related activities), resulted in distinct injury profiles for the ACL and PCL groups. These findings provide valuable information of the way specific injury patterns of cruciate ligament injuries occur, and subsequently may help clinicians with the diagnostic process of ACL and PCL injuries.

LEVEL OF EVIDENCE

III.

Intercondylar notch volume in patients with posterior cruciate ligament tears and tibial avulsion injuries: a study applying computed tomography

BACKGROUND

Two relatively common forms of injury exist in the posterior cruciate ligament (PCL) after the onset of trauma: PCL tear and tibial avulsion fracture. The mechanism for the occurrence of these different forms of injury is not known. Herein, we aimed to investigate this mechanism by comparing the intercondylar notch parameters between patients with PCL tears and those with PCL avulsion fractures of the tibial insertion.

METHODS

Fifty-three patients with PCL tears (37 male, 16 female: median age of 37 years: range 18-54 years) and 46 patients with avulsion fractures of tibial insertion (33 male, 13 female: median age of 33 years: range 18-55 years) were included in this study. Three-dimensional computed tomography (CT) was applied to measure the intercondylar notch width index and intercondylar notch volume. The intercondylar notch volume was simulated as the truncated-pyramid shape. Measurements of the top and bottom areas of this model were conducted on the slice containing the most proximal (S₁) and most distal (S₂) levels of Blumensaat's line. Femoral condyle height (h) was defined as the vertical distance between two parallel planes, and the volume was calculated as h(S₁ + S₂ + √(S₁S₂))/3. The values of S₁, S₂, h, notch volume, the body mass index (BMI), intercondylar notch width (NW), femoral condylar width (FW) and notch width index (NWI) were compared among the PCL tear and avulsion-fracture groups.

RESULTS

The results show a significant difference in the S₂ and normalized intercondylar notch volumes among patients with PCL tears and tibial avulsion injuries. Patients with PCL tears have smaller S₂ and intercondylar notch volumes than those with tibial avulsion. There were no significant differences between the two groups in S₁ or the 2D notch measurement parameters, such as the NW, FW and NWI. In addition, logistic regression analysis revealed notch volume and body mass index (BMI) as two significant independent predictors for PCL tears.

CONCLUSION

Decreased intercondylar notch volume and increased BMI are associated with an increased incidence of PCL tears. The occurrence of PCL tears and tibial avulsion injuries is influenced by the femoral intercondylar notch volume, and the measurement of the notch volume could be useful for identifying patients at risk for PCL tears.

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.

PCL insufficient patients with increased translational and rotational passive knee joint laxity have no increased range of anterior-posterior and rotational tibiofemoral motion during level walking

Passive translational tibiofemoral laxity has been extensively examined in posterior cruciate ligament (PCL) insufficient patients and belongs to the standard clinical assessment. However, objective measurements of passive rotational knee laxity, as well as range of tibiofemoral motion during active movements, are both not well understood. None of these are currently quantified in clinical evaluations of patients with PCL insufficiency. The objective of this study was to quantify passive translational and rotational knee laxity as well as range of anterior–posterior and rotational tibiofemoral motion during level walking in a PCL insufficient patient cohort as a basis for any later clinical evaluation and therapy. The laxity of 9 patient knees with isolated PCL insufficiency or additionally posterolateral corner (PLC) insufficiency (8 males, 1 female, age 36.78 ± 7.46 years) were analysed and compared to the contralateral (CL) knees. A rotometer device with a C-arm fluoroscope was used to assess the passive tibiofemoral rotational laxity while stress radiography was used to evaluate passive translational tibiofemoral laxity. Functional gait analysis was used to examine the range of anterior–posterior and rotational tibiofemoral motion during level walking. Passive translational laxity was significantly increased in PCL insufficient knees in comparison to the CL sides (15.5 ± 5.9 mm vs. 3.7 ± 1.9 mm, p < 0.01). Also, passive rotational laxity was significantly higher compared to the CL knees (26.1 ± 8.2° vs. 20.6 ± 5.6° at 90° knee flexion, p < 0.01; 19.0 ± 6.9° vs. 15.5 ± 5.9° at 60° knee flexion, p = 0.04). No significant differences were observed for the rotational (16.3 ± 3.7° vs. 15.2 ± 3.6°, p = 0.43) and translational (17.0 ± 5.4 mm vs. 16.1 ± 2.8 mm, p = 0.55) range of anterior–posterior and rotational tibiofemoral motion during level walking conditions for PCL insufficient knees compared to CL knees respectively. The present study illustrates that patients with PCL insufficiency show a substantial increased passive tibiofemoral laxity, not only in tibiofemoral translation but also in tibiofemoral rotation. Our data indicate that this increased passive multiplanar knee joint laxity can be widely compensated during level walking. Further studies should investigate progressive changes in knee joint laxity and kinematics post PCL injury and reconstruction to judge the individual need for therapy and effects of physiotherapy such as quadriceps force training on gait patterns in PCL insufficient patients.

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.

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.

The treatment of posterolateral knee instability with combined arthroscopic popliteus bypass and PCL reconstruction provides good-to-excellent clinical results in the mid-term follow-up

PURPOSE

The purpose of this study was to evaluate the clinical outcomes of patients who were treated with an arthroscopic popliteus bypass (PB) technique, in cases of a posterolateral rotational instability (PLRI) and a concomitant posterior cruciate ligament (PCL) injury of the knee.

METHODS

This was a retrospective case series in which 23 patients were clinically evaluated after a minimum of 2 years following arthroscopic PB and combined PCL reconstruction. Lysholm, Tegner and Knee Injury and Osteoarthritis Outcome scores as well as visual analog scales (VAS) for joint function and pain were evaluated. Posterior laxity was objectified with stress radiography and a Rolimeter examination. Rotational instability was graded with the dial test.

RESULTS

23 patients were available for follow-up, 46.0 ± 13.6 months after surgery. The median time interval from the initial injury to the surgery was 6.0 (3.5;10.5) months. The postoperative Lysholm Score was 95.0 (49-100); the Tegner Score changed from 6.0 (3-10) before the injury to 5.0 (0-10) at the follow-up examination (p = 0.013). The side-to-side difference on stress radiography (SSD) of posterior translation changed from 10.4 (6.6-14.8) mm before the injury to 4.0 (0.2-5.7) mm postoperatively (p < 0.01). Rotational instability was reduced to grade A (82.6%) or B (17.4%) (IKDC). The Rolimeter SSD was 2.0 (0-3) mm at the follow-up examination. VAS Function 0 (0-5), VAS pain 0 (0-6).

CONCLUSIONS

The arthroscopic PB graft technique provided good-to-excellent clinical results in the mid-term follow-up in patients with type A PLRI and concomitant PCL injury. However, an exact differentiation of lateral, rotational and dorsal instabilities of posterolateral corner (PLC) injuries is crucial, for the correct choice of therapy, as cases with lateral instabilities require more complex reconstruction techniques. Arthroscopic posterolateral corner reconstruction is a safe procedure with a high success rate in the mid-term follow-up.

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.

Dislocated hinge fractures are associated with malunion after lateral closing wedge distal femoral osteotomy

PURPOSE

To evaluate the incidence, morphology, and associated complications of medial cortical hinge fractures after lateral closing wedge distal femoral osteotomy (LCW-DFO) for varus malalignment and to identify constitutional and technical factors predisposing for hinge fracture and consecutive complications.

METHODS

Seventy-nine consecutive patients with a mean age of 47 ± 12 years who underwent LCW-DFO for symptomatic varus malalignment at the authors' institution between 01/2007 and 03/2018 with a minimum of 2-year postoperative time interval were enrolled in this retrospective observational study. Demographic and surgical data were collected. Measurements evaluating the osteotomy cut (length, wedge height, hinge angle) and the location of the hinge (craniocaudal and mediolateral orientation, relation to the adductor tubercle) were conducted on postoperative anterior-posterior knee radiographs and the incidence and morphology of medial cortical hinge fractures was assessed. A risk factor analysis of constitutional and technical factors predisposing for the incidence of a medial cortical hinge fracture and consecutive complications was conducted.

RESULTS

The incidence of medial cortical hinge fractures was 48%. The most frequent morphological type was an extension fracture type (68%), followed by a proximal (21%) and distal fracture type (11%). An increased length of the osteotomy in mm (53.1 ± 10.9 vs. 57.7 ± 9.6; p = 0.049), an increased height of the excised wedge in mm (6.5 ± 1.9 vs. 7.9 ± 3; p = 0.040) as well as a hinge location in the medial sector of an established sector grid (p = 0.049) were shown to significantly predispose for the incidence of a medial cortical hinge fracture. The incidence of malunion after hinge fracture (14%) was significantly increased after mediolateral dislocation of the medial cortical bone > 2 mm (p < 0.05).

CONCLUSION

Medial cortical hinge fractures after LCW-DFO are a common finding. An increased risk of sustaining a hinge fracture has to be expected with increasing osteotomy wedge height and a hinge position close to the medial cortex. Furthermore, dislocation of a medial hinge fracture > 2 mm was associated with malunion and should, therefore, be avoided.

LEVEL OF EVIDENCE

Prognostic study; Level IV.

[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.