High Yield Overview

PCL RECONSTRUCTION

Dashboard Injury | Posterior Drawer | Single vs Double Bundle

Critical PCL Reconstruction Points

Diagnosis

Posterior drawer test: 90° flexion, push tibia posteriorly. Sag sign: Tibia drops in 90° flexion. Quadriceps active test: Tibia moves forward with quad contraction.

Grading

I: 1-5mm, tibia anterior to medial femoral condyle. II: 6-10mm, tibia flush. III: greater than 10mm, tibia posterior. Grade III = surgery.

Surgical Indications

Grade III instability (greater than 10mm). Multiligament injury (especially with posterolateral corner). Symptomatic Grade II failing conservative. Athletes.

Killer Turn

Transtibial technique: Sharp angle as graft exits tibial tunnel ("killer turn"). Can abrade graft. Tibial inlay avoids this but requires posterior approach.

Mnemonic

DASHPCL Injury Features

Memory Hook:DASH = Dashboard, Anterior sag, Step-off lost, Higher grades!

Overview and Mechanism

The posterior cruciate ligament (PCL) is the primary restraint to posterior tibial translation. It is the thickest ligament in the knee.

Mechanism

Dashboard injury: Classic mechanism. Flexed knee, posterior force on proximal tibia (e.g., knee hitting dashboard in MVA).

Hyperflexion: Non-contact fall onto flexed knee.

Hyperextension: Can injure both cruciates.

Anatomy

Two bundles: Anterolateral (larger, tighter in flexion) and posteromedial (tighter in extension).

Tibial insertion: Posterior tibial fovea, well below articular surface.

Clinical Assessment

Examination

Posterior Drawer Test: 90° flexion, stabilize foot, push tibia posteriorly. Positive = increased laxity.

Sag Sign (Godfrey's Test): 90° hip and knee flexion, observe lateral profile. Tibia sags posteriorly compared to other side.

Quadriceps Active Test: 90° flexion, foot fixed, contract quads. PCL-deficient tibia moves anteriorly (from posteriorly subluxed position).

Dial Test: Assess posterolateral corner if associated injury suspected.

Grading

Grade I: 1-5mm translation, tibia still anterior to medial femoral condyle.

Grade II: 6-10mm, tibia flush with condyle.

Grade III: greater than 10mm, tibia posterior to condyle.

Management

Indications: Isolated Grade I-II. Low-demand patients. No associated injuries.

Treatment: Quadriceps strengthening is key (reduces posterior tibial sag). Brace. Activity modification. ROM exercises.

Outcomes: Many isolated PCL injuries function well non-operatively. Focus on quadriceps strength.

Evidence Base

📚 Fanelli and Edson

Clinical Implication: PCL recon improves stability in Grade III injuries.

Source: Arthroscopy 2002

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: PCL Injury

EXAMINER

"A 30-year-old man has posterior tibial sag and a positive posterior drawer with greater than 10mm translation. How do you manage him?"

EXCEPTIONAL ANSWER

This patient has a Grade III PCL injury, indicated by greater than 10mm posterior translation (tibia posterior to the medial femoral condyle). The sag sign and positive posterior drawer confirm PCL deficiency. This is a surgical indication. I would first assess for associated injuries, particularly the posterolateral corner (dial test, external rotation asymmetry), ACL, and MCL, as multi-ligament injuries are common with high-grade PCL injuries. I would obtain MRI to confirm the PCL tear, assess the character (midsubstance vs avulsion), and identify associated pathology. For isolated Grade III PCL, I would recommend reconstruction. My graft choice would be Achilles tendon allograft which provides a large, strong graft. Technique options include transtibial or tibial inlay. The transtibial technique is more common but the 'killer turn' where the graft exits the tibial tunnel can cause graft abrasion. The tibial inlay technique avoids this but requires a posterior approach. For femoral tunnel, I would place it in the anatomic footprint. Post-operatively, I would limit flexion initially to reduce tension on the graft, use a PCL brace for 3 months, and focus on quadriceps strengthening which is critical to counteract posterior tibial sag.

VIVA SCENARIOChallenging

Scenario 2: Multiligament Knee Injury - PCL + PLC Combined Reconstruction

EXAMINER

"A 28-year-old motorcyclist is referred to your clinic 6 weeks after a motorcycle accident. He sustained a knee injury from a dashboard-type mechanism during the collision. Initial management at the trauma center included immobilization and conservative treatment as there was no dislocation and neurovascular status was intact. However, he has persistent instability and pain. On examination, he has a significant posterior drawer (Grade III, greater than 10mm posterior translation), positive sag sign, and on dial testing at 30° and 90°, you note increased external rotation of 15° compared to the contralateral side at both angles, indicating combined PCL and posterolateral corner (PLC) injury. His knee varus stress test also shows opening at 30° flexion. He has full range of motion (0-130°) and no effusion. Plain radiographs show no fractures but stress views confirm the laxity. MRI confirms complete tears of the PCL (midsubstance), lateral collateral ligament (LCL), and popliteus tendon, consistent with PLC injury. There is no ACL injury. He is an active patient who wants to return to recreational sports and his physically demanding job as a firefighter. How do you counsel him and what is your surgical plan?"

EXCEPTIONAL ANSWER

This patient has a multiligament knee injury, specifically combined PCL and posterolateral corner (PLC) injury, which represents a complex reconstructive challenge. The Grade III posterior drawer confirms complete PCL tear, and the positive dial test at both 30° and 90° with increased external rotation (15° asymmetry) is diagnostic of PLC injury. When the dial test is positive at 30° only, it suggests isolated PLC; positive at both 30° and 90° indicates combined PCL-PLC injury, which is the case here. This is the second most common multiligament injury pattern after ACL-MCL. I would counsel him that this requires surgical reconstruction of both structures - isolated PCL or PLC reconstruction alone will fail if the other structure is not addressed, as the forces will overload the single repair and cause recurrent instability. The timing is appropriate at 6 weeks post-injury - multiligament reconstructions are typically performed at 2-6 weeks to allow soft tissue healing and inflammation to settle while avoiding chronic scarring that makes surgery more difficult. For combined PCL-PLC reconstruction, I have two main approaches: single-stage combined reconstruction (PCL + PLC in one surgery) or staged reconstruction (PLC first, then PCL). I would favor single-stage reconstruction in this case as the patient is young, motivated, has good soft tissue envelope, and both injuries are acute with no evidence of chronic changes. Single-stage reduces overall treatment time, anaesthetic exposure, and may have synergistic healing. However, the post-operative rehabilitation is more challenging with restrictions for both reconstructions. My surgical plan would be: (1) PCL reconstruction using Achilles tendon allograft via transtibial or tibial inlay technique - I would favor tibial inlay for multiligament cases to avoid the killer turn stress and provide more robust fixation in this unstable knee; (2) PLC reconstruction - multiple techniques available, but I would use a modified Larson technique with hamstring autograft (semitendinosus) or allograft recreating the LCL and popliteofibular ligament. The graft is routed from the fibular head (LCL insertion) to the femoral epicondyle and then to the popliteus insertion on the tibia. Some surgeons perform an anatomic reconstruction of all three PLC structures (LCL, popliteus, popliteofibular), but modified Larson is biomechanically sound and technically simpler; (3) Sequence: I would perform the PLC reconstruction first, then the PCL - this allows me to address the posterolateral instability which can complicate PCL tunnel placement and graft tensioning. Post-operatively: hinged knee brace locked in extension for ambulation, limit flexion to 60-70° for first 6 weeks to protect PCL graft, no varus stress or external rotation to protect PLC for 3 months, progressive weight-bearing as tolerated with brace, quadriceps strengthening critical. Return to sports 9-12 months minimum. I would counsel him that combined PCL-PLC reconstruction has good but not perfect outcomes - he can expect 70-80% to return to sports, but residual laxity (5-10% persistent grade I-II laxity) is common even with anatomic reconstruction. Firefighting with its high physical demands may be challenging.

VIVA SCENARIOCritical

Scenario 3: Failed PCL Reconstruction - Graft Failure and Revision Strategy

EXAMINER

"You are seeing a 32-year-old former college rugby player in your revision knee surgery clinic. He underwent PCL reconstruction 3 years ago at another institution using a hamstring autograft via transtibial technique for an isolated Grade III PCL injury sustained during rugby. He did well initially and returned to recreational rugby at 12 months post-operatively. However, over the past 12-18 months he has developed progressive posterior knee instability with the knee 'giving way' when decelerating or going downstairs. He has also developed medial and patellofemoral knee pain. He stopped playing rugby 6 months ago due to the instability and pain. On examination, he has a positive posterior drawer test with approximately 10-12mm of posterior translation (Grade III), positive sag sign, mild quadriceps atrophy, and patellofemoral crepitus with pain on patellar grind. His range of motion is 0-135° (full). Dial test is negative (no PLC injury). You review his operative report from the original surgery which states that a four-strand semitendinosus-gracilis autograft was used, transtibial technique, femoral tunnel placed 'in the PCL footprint,' tibial tunnel from anteromedial tibia, grafts tensioned at 90° flexion and fixed with interference screws. You obtain new imaging: plain radiographs show mild patellofemoral and medial compartment degenerative changes, and the tibial tunnel is visible and appears to be in reasonable position; MRI shows that the PCL graft is present but appears attenuated and stretched with high T2 signal indicating degeneration, there is posterior tibial translation on the sagittal images, and early cartilage damage in the medial femoral condyle and patella. The patient is frustrated and asks what went wrong and whether revision surgery can help him. How do you counsel him and what is your management plan?"

EXCEPTIONAL ANSWER

This is a case of failed PCL reconstruction with recurrent Grade III posterior instability at 3 years post-operatively, which is a challenging scenario requiring careful analysis of the failure mechanism and realistic counseling about revision surgery outcomes. I would first acknowledge the patient's frustration and validate that this is an unfortunate outcome - PCL reconstruction has a 10-20% failure rate even with good technique, so this is not unprecedented. Looking at the history and operative details, there are several potential causes of failure that I would discuss with him: (1) Graft choice - hamstring autograft (semitendinosus-gracilis) is a reasonable choice but may be less robust than Achilles allograft for PCL reconstruction. The PCL is the thickest ligament in the knee and experiences high loads - a four-strand hamstring may stretch over time, particularly in a high-demand athlete. Many surgeons prefer Achilles allograft for primary PCL reconstruction due to larger cross-sectional area and strength; (2) Transtibial technique with 'killer turn' - the original surgery used transtibial approach where the graft exits the tibial tunnel at an acute angle (the 'killer turn'). This creates a stress riser where the graft can abrade against the edge of the tunnel with repeated flexion-extension cycles, leading to gradual graft attenuation and stretching. The tibial inlay technique avoids this issue by fixing the graft to a flat posterior tibial surface, but was not used in his case; (3) Tunnel position - the report states 'PCL footprint' for femoral tunnel but without intraoperative images or CT, I cannot verify this was truly anatomic. Non-anatomic tunnel position (too anterior or too posterior) can lead to graft malfunction and failure; (4) Graft tensioning - tensioning at 90° flexion is standard, but some evidence suggests tensioning at 70-90° with anterior tibial drawer applied may better restore posterior stability. However, this is controversial; (5) Biology - even with perfect technique, some grafts simply don't incorporate well or the patient's biology doesn't support graft healing and remodeling, leading to stretching; (6) Patient factors - return to rugby at 12 months with high-demand cutting and contact likely placed significant stress on the graft before full maturation (grafts take 18-24 months to fully mature), potentially causing early microfailure that progressed over time. The recurrent posterior instability has now led to secondary problems: medial compartment overload (posterior tibial translation causes increased contact stress medially and medial femoral condyle cartilage damage on MRI), and patellofemoral overload (altered kinematics with posterior sag changes patellar tracking, causing patellofemoral pain and early arthritis visible on X-rays). This is the natural history of chronic PCL deficiency - progressive degenerative changes. Regarding revision PCL reconstruction, I need to counsel him with realistic expectations: (1) Revision PCL reconstruction is technically more challenging than primary - scar tissue, tunnel widening, altered anatomy make graft passage and fixation difficult; (2) Outcomes are inferior to primary reconstruction - success rates for revision PCL are 60-70% (compared to 80-90% primary), with higher rates of persistent laxity (30-40% vs 10-20%), stiffness, and arthritis progression; (3) He already has early arthritis (medial and patellofemoral compartments) which will likely progress regardless of revision surgery - PCL reconstruction does not reverse existing cartilage damage; (4) At age 32 with degenerative changes starting, his window for successful joint preservation is narrowing. If he were to undergo revision, I would recommend: (1) Achilles tendon allograft (larger, stronger than hamstring), (2) Tibial inlay technique to avoid killer turn that likely contributed to original failure, (3) Careful attention to femoral tunnel position (may need CT to plan tunnels, potentially use original tunnels if well-positioned or stage with bone grafting if malpositioned), (4) Post-operative bracing and restrictions similar to primary (limit flexion 6 weeks, brace 3 months, gradual return), (5) No return to rugby - revision graft cannot tolerate high-demand pivoting sports, recreational activities and gym only. I would offer him two pathways: (1) Attempt revision PCL reconstruction with understanding of 60-70% success, 30-40% persistent laxity, need to modify activity permanently (no rugby), and acceptance that arthritis will likely progress requiring TKR in his 50s-60s; or (2) Non-operative management with quadriceps strengthening, activity modification, brace for high-demand activities, NSAIDs, and plan for TKR when symptoms warrant (likely 15-20 years). Given his age (32), I would lean toward offering revision surgery as it may provide 10-15 years of improved function and delay TKR, but only if he has realistic expectations and commits to activity modification. If he wants to return to rugby, I would counsel against surgery as it will fail again.

PCL RECONSTRUCTION

High-Yield Exam Summary