Experimental validation of a new technique for the assessment of posterior tibial translation (ABC angle) after posterior cruciate ligament rupture

Background The aim of this cadaver study was to evaluate an original technique for measuring posterior tibial translation based on an angle value instead of a distance value, with and without posterior stress application. It was hypothesized that an angle measurement of the posterior tibial translation would confirm the presence of a PCL tear with the knee flexed and completely extended. Method Using fresh cadavers, a set of strict lateral views were taken by fluoroscopy with the knee at 0°, 45° and 90° flexion on the intact knee and after transecting the PCL. The primary endpoint was the change in the posterior translation measured using a new technique, the ABC angle. This measurement was compared to the conventional posterior translation distance measurement with and without a posterior stress placed on the knee. Results Application of a posterior stress revealed clear changes in posterior translation after PCL transection with the knee at 0° for the angle technique and at 45° and 90° for the two techniques (p < 0.05). Contrary to the reference method, the ABC angle method found a statistically significant difference in posterior translation with the knee in extension. Conclusion Our technique provides a reliable radiographic measurement of posterior translation with the knee in extension, which should make it easier to acquire radiographs in patients who have pain with knee flexion. This angular measurement also has the advantage of not needing length calibration contrary to the reference technique. Level of evidence IV

Sequential Changes in Posterior Tibial Translation After Posterior Cruciate Ligament Reconstruction: Risk Factors for Residual Posterior Sagging

Background: Residual posterior sagging may occur after posterior cruciate ligament (PCL) reconstruction (PCLR), yet when it mainly occurs is not fully understood. Purpose: To elucidate sequential changes in radiographic posterior tibial translation (PTT) after PCLR. Study Design: Case-control study; Level of evidence, 3. Methods: The authors retrospectively investigated the radiographic findings from 22 patients who underwent bisocket double-bundle PCLR for isolated PCL injury with at least 2 years of follow-up (mean, 4.5 years; range, 2-10 years). Injury severity was assessed using PTT on lateral radiographs with gravity sag views and was stratified according to side-to-side difference in the tibial-femoral stepoff: grade 1 (<5 mm), grade 2 (5 to <10 mm), or grade 3 (≥10 mm). Measurements were taken preoperatively and then immediately, 3 months, 6 months, 1 year, and ≥2 years postoperatively. The authors also investigated the risk factors for residual posterior sagging, indicated when PTT was ≥5 mm (grade ≥2) at the minimum 2-year follow-up. Results: Preoperatively, 13 patients had a grade 2 injury, and 9 had grade 3 injury. The PTT, restored immediately after PCLR, significantly increased at 3 months ( P < .001) but remained unchanged thereafter ≥2 years. There were 7 cases of postoperative PTT ≥5 mm on radiographs. Patients with residual posterior sagging had significantly larger mean PTT than did those without residual posterior sagging at all time points except for immediately postoperatively (preoperatively, 9.1 ± 1.6 vs 12.2 ± 2.3 mm; 3-month follow-up, 2.7 ± 1.6 vs 7.0 ± 1.8 mm; ≥2-year follow-up, 3.4 ± 1.0 vs 6.5 ± 1.4 mm; P < .001 for all). Multivariate logistic regression analysis showed that preoperative grade 3 injury was independently associated with residual posterior sagging (OR, 26.809; 95% CI, 1.257-571.963; P < .001). Conclusion: The initially reduced postoperative PTT significantly increased within 3 months using conventional rehabilitation protocols, but no progression was observed up to 4.5 years after PCLR. Preoperative grade 3 injury was independently associated with residual posterior sagging.

Anatomy and Biomechanics of the Posterior Cruciate Ligament

Posterior cruciate ligament (PCL) injuries are often encountered in the setting of other knee pathology and sometimes in isolation. A thorough understanding of the native PCL anatomy is crucial in the successful treatment of these injuries. The PCL consists of two independent bundles that function in a codominant relationship to perform the primary role of resisting posterior tibial translation relative to the femur. A secondary role of the PCL is to provide rotatory stability. The anterolateral (AL) bundle has a more vertical orientation when compared with the posteromedial (PM) bundle. The AL bundle has a more anterior origin than the PM bundle on the lateral wall of the medial femoral condyle. The tibial insertion of AL bundle on the PCL facet is medial and anterior to the PM bundle. The AL and PM bundles are 12-mm apart at the center of the femoral origins, while the tibial insertions are more tightly grouped. The different spatial orientation of the two bundles and large distance between the femoral centers is responsible for the codominance of the PCL bundles. The AL bundle is the dominant restraint to posterior tibial translation throughout midrange flexion, while the PM bundle is the primary restraint in extension and deep flexion. Biomechanical testing has shown independent reconstruction of the two bundles that better reproduces native knee biomechanics, while significant differences in clinical outcomes remain to be seen. Stress X-rays may play an important role in clinical decision-making process for operative versus nonoperative management of isolated PCL injuries. Strong understanding of PCL anatomy and biomechanics can aid surgical management.

Double Bundle Posterior Cruciate Ligament Reconstruction in 100 Patients at a Mean 3 Years Follow up: Outcomes were Comparable to an Anterior Cruciate Ligament Reconstructions

Objectives: 1) To report on the outcomes after double-bundle PCL reconstructions in isolated versus combined injuries and acute versus chronic PCL tears and 2) to compare the outcomes of isolated double-bundle PCL reconstruction (DB PCLR) to isolated ACL reconstruction (ACLR). Methods: All patients who underwent a primary arthroscopic assisted DB PCLR for grade-III isolated or combined PCL injuries between May 2010 and March 2015 were reviewed. Patient reported outcome scores (Lysholm, Tegner, Western Ontario and McMaster Universities Arthritis Index (WOMAC), 12 item Short Form Health Survey (SF-12) Physical Component Summary (PCS) and patient satisfaction with outcome) and objective posterior stress radiographs were collected preoperatively and at a minimum of two years postoperatively. Cohort subanalyses comparing isolated versus combined, and acute versus chronic PCL reconstructions were also performed. Patients who underwent isolated ACLR over the same inclusion period were selected as a comparison group. Results: One hundred patients that underwent DB PCLR were included in this study. There were 31 isolated PCL injuries and 69 combined PCL injuries and the mean follow-up was 2.9 years (range 2-6 years). The median Tegner activity score improved from 2 to 5, Lysholm from 48 to 86, WOMAC from 35.5 to 5, and SF-12 PCS from 34 to 54.8 (all p values <0.001). The mean side-to-side difference (SSD) in posterior tibial translation on kneeling stress radiographs improved from 11.0 mm preoperatively to 1.6 mm postoperatively (p<0.001). There were no significant differences in postoperative functional scores between isolated PCL reconstructions and combined PCL reconstructions (all p values >0.229). The mean SSD in postoperative posterior tibial translation on stress radiographs was 1.2 ± 1.1 mm for isolated PCL tears and 1.7 ± 2.2 mm for combined PCL tears. The improvement in posterior tibial translation from preoperative to postoperative was significant for both the isolated and combined PCL injury groups (p<0.001). Only the Tegner score (p<0.001) and patient satisfaction (p=0.011) were significantly different postoperatively between acute and chronic reconstructions, both favoring acutely treated PCL injuries. The mean SSD in posterior tibial translation on stress radiographs improved from 11.6 ± 3.1 mm preoperatively to 1.9 ± 2.5 mm postoperatively (p<0.001) for acute PCL tears, and 10.3 ± 3.7 mm to 1.2 ± 1.0 mm (p<0.001) for chronic PCL tears. There were no significant differences in postoperative outcome scores between patients that underwent an isolated ACLR or isolated DB PCLR [all p values >0.064]. Conclusion: Significantly improved functional and objective outcomes were observed after anatomic-based DB PCLR at a mean 3 years follow-up, regardless of concomitant ligamentous pathology or timing to surgery. Posterior tibial translation was restored to near normal after DB PCLR. Additionally, contrary to previous reports, similar results were achieved compared to a control isolated ACLR cohort. [Table: see text][Figure: see text]

Vascular Complications in Arthroscopic Repair Of Posterior Cruciate Ligament

Introduction: Posterior cruciate ligament is the primary stabilizer of the knee. Among the potential complications in arthroscopic repair of this ligament, there are vascular lesions, due to laceration, thrombosis and injury of the intima of the popliteal artery. We used one case to show the vascular complications that may arise in arthroscopic repair of the posterior cruciate ligament, how to handle it and the results. Methods: One patient, 33 years old, with a history of traffic accident. In a physical exam the patient shows pain and swelling of the knee, positive posterior drawer test and positive Godfrey test. X-rays on the knee show posterior tibial translation and MRI a complete fibers rupture at the middle third of the posterior cruciate ligament. An arthroscopic repair surgery was scheduled three weeks after trauma, with PCL reconstruction using simple band technique.After surgical intervention, hemostatic cuff was released, no peripheral pulse, paleness and coldness of the member was confirmed. An arteriography was carried out, which confirmed absences of distal vascular filling in the popliteal artery. An urgent referral was carried out with Vascular Surgery Services, who had been informed of the surgery previously (a notification that is part of our routine for this kind of interventions). Arteriorrhaphy and venorrhaphy of the popliteal arteries was fulfilled 12 hours later, with a leg fasciotomy. Daily monitoring was performed, and after 72 hours, muscle necrosis is seen with wound drainage, analysis shows presence of gram-negative bacilli, Proteus Mirabilis-Pseudomonas spp and the lab results showed leukocytes: 8.700/ml, ESR: 58, CRP: 48. A new surgery is performed with complete resection of the anterior external compartment of the leg, and a system of continuous cleansing is applied with physiological saline solution and boric acid for 14 days until drainage is eliminated. Vancomycin and ceftazidime EV was indicated for 14 days and, after a good evolution of the wounds, patient is discharged from hospital with Sulfamethoxazole/trimethoprim 160mg/800mg to be taken orally for 14 days. Results: After treatment with oral antibiotic is completed, wounds progress positively. Foot in equinus position, has positive distal pulses with distal sensibility. Use of a thermoforming brace is indicated for movement. Vascular Surgery Services are currently following patient’s evolution. An ankle arthrodesis surgery is evaluated for the future. Conclusion: Combined injuries that result in a posterior tibial translation over 15 mm and, those that come along with injuries in the anterior cruciate ligament or posterior lateral structures of the knee, should be repaired through surgery. Vascular lesion caused by laceration, thrombosis or injury of the intima of the popliteal artery, mainly during perforation and preparation of tibial tunnel, is a serious lesion. Although these vascular lesions during arthroscopy are complications relatively rare, a potential risk should be considered, with consequences that could be fatal for the extremity and for patient’s life when bleeding is involved. In those cases, urgent treatment is imperative, that is the reason we believe it is safe to coordinate with Vascular Surgery Services before the surgery is carried out.