An evaluation of posterior cruciate ligament reconstruction surgery

This is a descriptive study conducted in Hazrat Rasoul Hospital in Tehran, Iran affiliated to Iran University of Medical Sciences, Tehran, Iran. The center is a referral center for knee surgery for a population living in Tehran city and is among the few hospital in the country where PCL surgery is performed.

Any patient who referred with a diagnosis of acute or chronic tear of PCL with signs of functional deficit, pain, or instability of grade 2 or higher (based on the posterior drawer test) and had a displacement of more than 5 mm on stress x-ray, during 2004 up to 2018 was included in this report. Those who did not refer for their follow-up visits, individuals with concomitant knee deformity who underwent corrective osteotomy without any other reconstructive surgeries, and finally individuals with neuromuscular diseases or severe degenerative joint disease, were excluded from the study.

PCL tear was diagnosed based on physical examination and magnetic resonance imaging (MRI). Physical examination included posterior drawer test (PDT) and palpation of medial and lateral step-off, varus and valgus stress tests and evaluation of posteromedial and posterolateral corners. More specifically and especially in patients with isolated PCL tear, PDT was performed in acute flexion of the knee, during which palm of the examining hand was placed on the tibial tuberosity and anterior plateau and fingers of the same hand were placed on the patella and femoral condyles, while pushing the tibia back by the palm, posterior translation of the tibial plateau in relation to the femoral condyles was felt. The same process was performed on the uninvolved contralateral knee to determine the severity of the instability (supplement 1).

Among patients with grade 2+ to 3+ instability (in PDT), single PCL injury and no concomitant collateral ligament injury, a single tunnel PCL reconstruction of the anterolateral bundle was conducted. For more severe grade 3+ instability (in PDT) with substantial sagging of the knee, double tunnel PCL reconstruction was used. Depending on the size of the knee and based on the clinical assessment of the surgeon, double femoral tunnel - double tibial tunnel or double femoral tunnel - single tibial tunnel PCL reconstruction was used. For those who had posteromedial corner injuries a double tunnel PCL reconstruction was used with a posteromedial corner reconstruction. In patients with concomitant collateral ligament injuries, depending on the type of injury, double tunnel PCL and arthroscopic assisted tibialis posterior allograft MCL reconstruction or double tunnel PCL and arthroscopic popliteus tendon allograft reconstruction and the modified Larson technique was used.

Under spinal or general anesthesia, the involved limb was hanged from the end of the operating table and was prepared so that access to the posterior part of the knee and creation of the posteromedial (and if needed posterolateral) arthroscopy portal was feasible. Anterior working portals included high and low anterolateral portals and a high anteromedial portal.

For the single tibial-single femoral tunnel technique, first the femoral tunnel is created using a low anterolateral arthroscopic portal through which a guide pin is placed. Using a drill bit which has the same diameter as the looped tibialis posterior allograft tendon we then check that the footprint of the anterolateral bundle of the PCL is adjusted. Through the low anterolateral portal we pass the 30 degree scope into the posteromedial side of the popliteal fossa, adjacent to the remnant of the PCL, we enter into the space of the posteromedial corner and under a direct vision, the posteromedial portal is created. Care must be taken not to injure the saphenous nerve and vein and the popliteal neurovascular complex. Using a radiofrequency probe, through a posteromedial portal, under direct vision, from the posterior of the remnant of the tibial attachment of the PCL, while the face of the probe is towards the bone, dissection is done until the proximal border of the popliteus muscle is reached. After which, through the high anteromedial portal, jig of the PCL is entered into the popliteal space and under visual control by the arthroscopy scope through the posteromedial portal, the tip of the jig must sit on the anatomic tibial attachment site of the PCL. The angle of the jig is adjusted to 60 degrees. Tip of the newly commercially available PCL jigs are wide enough to stop and prevent extrusion of the tip of the guide pin into the popliteal fossa, especially if used under direct vision through the posteromedial arthroscopy portal, consequently there is no need to use other protective instruments such as arthroscopy curates or etc. Using a guide pin from the anteromedial part of the tibial plateau, medial to the tibial tuberosity we drill through the jig until the tip of the guide wire is visible in the correct position. It should be mentioned that with adequate vision much care should be given to protect the popliteal artery and vein. Especially for novice surgeons it is mandatory to check the position and direction of the guide wire by the C-Arm. After which using a drill bit, an appropriate tibial tunnel is created. Then the tibialis posterior allograft which is loaded with an endobutton is entered through the anteromedial arthroscopy portal of the knee. We can also enter the allograft through the tibial tunnel and then pass it into the joint and finally in the femoral tunnel. The head of the allograft which has the endobutton, is drawn from inside of the knee to the femoral tunnel and is then flipped over the medial femoral condyle. Considering that for allografts we used double fixation, in addition to an endobutton, a bio-interference screw is also placed inside the femoral tunnel. Thereafter, the force of the anterior drawer is applied into the proximal tibia until correction of the medial step-off in 90 to 70 degrees flexion of the knee, furthermore the tibial tunnel is fixed by one bio-interference screw and as double fixation the end of the tendon is also fixed to the tibial plateau by one tendon staple (Figs. 1 and 2).

In the double femoral tunnel technique, two single strand sections of tibialis posterior allograft are prepared. Anterolateral femoral tunnel is created in the same way as in the single tunnel reconstruction technique and for the posteromedial tunnel, from the low anterolateral arthroscopy portal, a guide pin is inserted in the anatomic footprint of the posteromedial bundle of PCL just inferior to the meniscofemoral ligament during which care must be taken not to injure the meniscofemoral ligament, moreover a drill bit of appropriate size is used to create the tunnel. For the double femoral tunnel and single tibial tunnel PCL reconstruction, we create an open-ended anterolateral tunnel and a closed-ended posteromedial femoral tunnel (Fig. 3). In this way at the time of fixation, first we fix the femoral side of the posteromedial bundle by a bio-interference screw using the inside-out technique and then we put tension on all strands of the graft in almost knee extension and we fix both grafts in the tibial tunnel, after which we flex the knee and place tension on the anterolateral bundle (the open-ended tunnel) from the femoral side and finally we fix the femoral tunnel of the anterolateral bundle in 90 to 70 degrees of flexion using the outside-in technique. For augmentation fixations, we tie the non-absorbable sutures of the proximal end of the grafts over the medial femoral condyle and we augment the distal end of the grafts by one tendon staple on the medial tibial plateau just distal to the orifice of the tibial tunnel (Fig. 3).

For the double femoral - double tibial tunnel reconstruction, first the femoral tunnel of both bundles is fixed from inside of the joint by bio-interference screws in 90 degrees knee flexion then the tibial side of the posteromedial bundle is fixed in full knee extension and the tibial side of the anterolateral bundle is fixed in 70–90 flexion.

For PCL we only use tibialis posterior or tibialis anterior allografts.

For the first 6 months, follow-ups were different according to type of injury as either isolated PCL injury or combined injury, and based on the attending physician’s clinical assessment. Generally, after surgery patients were visited weekly for the first 2 weeks, after which for the next 3 months patients were followed every 3 weeks. After this period patients were given a follow-up at 6 months from their surgery which was then shifted to annual follow-ups. For evaluation of knee stability at follow-up visits, a bilateral kneeling stress radiography technique was used. This method of assessment was used to assess stability because of its easy applicability, faster response and relative low cost [14].

The first-week postoperative care included a simple knee immobilizer brace, no range of motion (ROM), partial weight bearing in the brace (in cases of no meniscus repair or collateral injury or reconstruction), isometric quadriceps exercises, and ankle pump.

In the second week, gentle passive and active ROM in the prone position was given and knee extension exercises were started.

After 2 weeks, straight leg raising was initiated and at the fourth week, depending on the condition of the quadriceps muscle, the knee immobilizer brace was removed. At 6 weeks, bilateral crutches were changed to a single crutch on the uninjured side.

Data on age, sex, job, time period between initial injury and surgery, type of trauma, chief complaint of patients, side of injury, type of injury as either single PCL injury or combined injury, type of PCL surgery, type of graft used for surgery, period of follow-up, pre- and PDT grade, Cincinnati knee rating scale (CKRS) before and after surgery, range of motion (ROM) before and after surgery, and complications, were recorded for each patient.

Type of trauma was categorized as traffic accidents, sports related injuries, and other types of injuries (falling down and etc.) which were classified as miscellaneous.

Patients’ chief complaints were either instability or instability and pain of the knee.

Type of PCL surgery was classified as single tibial - single femoral tunnel, single tibial - double femoral tunnel, and double tibial - double femoral tunnel.

Type of graft used was either autograft or allograft.

Surgery related complications were categorized as infections, arthrofibrosis and motion stiffness, and deep venous thrombosis.

Associated injuries included medial and lateral meniscal injuries, chondral lesions, ACL tear, popliteus and patellar tendon, posteromedial and posterolateral corner injuries.

In order to measure surgery related outcomes, the CKRS [15] was used. Multiple outcome measuring systems have been introduced, however only two have had acceptable validity and reliability, one of which is the CKRS. This measure includes indexes such as swelling of the knee, pain, giving away, overall daily activity level, walking, use of stairs, running activity, and jumping and twisting. The index has been shown to have high test reliability and validity in ACL injuries and has been also used in the context of PCL injuries [16, 17]. The index was measured 1 day before surgery and at final follow-up.

Using the kneeling stress x-ray, posterior displacement was measured and compared to the contralateral uninvolved knee. For obtaining the stress x-ray, the patient was asked to bend their knee at 90 degrees and to put their whole weight on their tibial tubercle. For the measurement and calculating the amount of displacement, one point was defined along the posterior cortex 10 cm from the joint line distal to the tibial plateau. Following which a line was drawn from this point parallel to the posterior cortex directed toward the knee joint. The most posterior point of the Blumensaat line was also marked. Finally a perpendicular line from the Blumensaat line was drawn to intersect the first line. Accordingly, the distance was measured and reported as the amount of displacement.

All patients’ personal data were secure throughout the study in order to protect anonymity of the patients. All patients gave their written and informed consent to enter the study. Study protocol has been approved by the Institutional Review Board of Fasa University of Medical Sciences (Ethics code #IR.FUMS.REC.1396.272).