Can Anatomic Posterolateral Corner Reconstruction Using a Fibular Tunnel Restore Fibular Footprints of the Posterolateral Complex? A Cadaveric Study

Influence and Clinical Significance of Knee Flexion Angle on the Anatomic Course of the Common Peroneal Nerve in the Posterolateral Corner of the Knee Joint

Background

Detailed knowledge of the anatomic course of the common peroneal nerve (CPN) is crucial for the surgical treatment of the posterolateral corner (PLC) of the knee.

Purpose

To investigate the relationship of the CPN to the PLC of the knee at different flexion angles.

Study Design

Descriptive laboratory study.

Methods

Ten healthy volunteers were recruited to undergo magnetic resonance imaging (MRI) of the knee joint at knee flexion angles of 0°, 30°, 60°, 90°, and 120°. MRI scans at 3 levels (joint line, tibial cut, and fibular tip) were evaluated to determine (1) the distance from the CPN to the PLC and (2) the distances between the CPN and the anterior-posterior and medial-lateral tibial axes. A 3-dimensional model of the knee joint created from MRI scans of a single participant was used to simulate the creation of a fibular tunnel for PLC reconstruction and investigate the relationship between the CPN, fibular tunnel, and guide pin.

Results

The CPN moved posteromedially with increased knee flexion angles. As the flexion angle increased, the distances from the CPN to the anterior-posterior axis and the PLC increased significantly, while the distance to the medial-lateral axis decreased significantly at all 3 measurement levels. The distances between the CPN and anterior-posterior and medial-lateral axes were significantly different among the different knee flexion angles at the different measurement levels. There were no significant differences in the mean distance from the CPN to the posterolateral border of the tibial plateau between 0° and 30° of flexion at the fibular tip level (P = .953). There were statistically significant differences in the distance from the CPN to the PLC of the tibial plateau at the different measurement levels. The 3-dimensional model demonstrated that the position of the CPN relative to the guide pin and the bone tunnel undergoes changes during knee flexion.

Conclusion

Changes in the knee flexion angle produced corresponding changes in the course of the CPN on the posterolateral aspect of the knee joint. The CPN moved posteromedially with increased knee flexion angles.

Clinical Relevance

Increasing the knee flexion angle during PLC reconstruction can effectively avoid direct injury of the CPN.

The distance between the fibular collateral ligament tunnel and the common peroneal nerve allows a posterolateral corner reconstruction without neurolysis

PURPOSE

The most popular knee posterolateral corner (PLC) reconstruction techniques describe that a common peroneal nerve (CPN) neurolysis must be done to safely address the posterolateral aspect of the knee. The purpose of this study was to measure the distance between the CPN and the fibular insertion of the FCL in different degrees of knee flexion in cadaveric specimens, to identify if tunnel drilling could be done anatomically and safely without a CPN neurolysis.

METHODS

Ex vivo experimental analytical study. Ten fresh frozen human knees were dissected leaving FCL and CPN in situ. Shortest distance from the centre of the FCL distal tunnel and CPN was measured (antero-posterior and proximal-distal wire-nerve distances) at 90°, 60°, 30°, and 0° of knee flexion. Measurements between different flexion angles were compared and correlation between knee flexion angle and distance was identified.

RESULTS

The mean distance between the FCL tunnel and the CPN at 90° were 21.15 ± 6.74 mm posteriorly (95% CI: 16.33-25.97) and 13.01 ± 3.55 mm distally (95% CI: 10.47-15.55). The minimum values were 9.8 mm posteriorly and 8.9 mm, respectively. These distances were smaller at 0° (p ≤ 0.017). At 90° of knee flexion, the mean distance from the fibular tip to the CPN distally was 23.46 ± 4.13 mm (20.51-26.41).

CONCLUSION

Anatomic localization and orientation of fibular tunnels can be done safely while avoiding nerve neurolysis. Further studies should aim to in vivo measurements and results.

Comparison of Arthroscopic versus Open Placement of the Fibular Tunnel in Posterolateral Corner Reconstruction

INTRODUCTION

 Precise fibular tunnel placement in posterolateral corner (PLC) reconstruction is crucial in restoring rotational and lateral stability. Despite the recent progress of arthroscopic PLC reconstruction techniques, landmarks for arthroscopic fibular tunnel placement and a comparison to open tunnel placement have not yet been described. This study aimed to (1) identify reasonable soft-tissue and bony landmarks, which can be identified by either arthroscopy, fluoroscopy, or open surgery in anatomic fibular tunnel placement and (2) to compare accuracy and reliability of arthroscopic fibular tunnel placement with open surgery.

MATERIALS AND METHODS

 In a retrospective study, 41 magnetic resonance images (MRIs) of the knee were analyzed with emphasis on distances of an ideal anatomic fibular tunnel to 11 soft-tissue and bony landmarks. Subsequently, in eight cadaver knees, the ideal fibular tunnel was created arthroscopically and with a standard open technique from antero-latero-inferior to postero-medio-superior with a 2-mm K-wire. Positions of both tunnels were compared on postinterventional computed tomography scans.

RESULTS

 Based on MRI measurements, the anatomic tunnel entry should be 14.50 (±2.18) mm distal to the tip of the fibular styloid and 10.76 (±1.37) mm posterior to the anterior edge of the fibula. The anatomic fibular tunnel exit was located 12.89 (±2.35) mm below the tip of the fibular head. Arthroscopic fibular tunnel placement was reliable in all cases. Instead, in five out of the eight cases with open surgery, the fibular tunnel crossed the defined safety distance to the closest cortical edge/tibiofibular joint (distance < 8 mm).

CONCLUSIONS

 Reliable soft-tissue and bony landmarks of the fibular head allow arthroscopic anatomic fibular tunnel placement in PLC surgery, which shows a lower risk of tunnel malposition compared with open surgical techniques. Future studies will have to show whether clinical results of arthroscopic PLC reconstruction are in line with this study's technical results.

LEVEL OF EVIDENCE

 Level III.

Salvage Fixation With a Single Nitinol Compression Staple for a Lateralized Fibular Tunnel in Posterolateral Corner Reconstruction of the Knee

Recognition and treatment of injuries to the posterolateral (PLC) corner of the knee have increased in recent decades. Despite advancements in surgical technique, complications can occur in up to 20% of PLC reconstructions. Lateralization of the fibular tunnel during drilling is a common intraoperative pitfall and can lead to cortical breach or fibular head fracture after graft tensioning. Compression staples have been increasingly used for fracture fixation in the hand, foot, and ankle. Because of its pseudo-elastic properties, insertion of a low-profile, compressive Nitinol staple could serve as an intraoperative salvage technique to reinforce and prevent failure through a thin lateral cortex of the fibular head. The purpose of this Technical Note is to describe a reproducible technique for the implementation of a Nitinol staple for reinforcement of a lateralized fibular tunnel in posterolateral corner reconstruction.

Evidence-Based Clinical Anatomy of the Popliteofibular Ligament and Its Importance in Orthopaedic Surgery: Cadaveric Versus Magnetic Resonance Imaging Meta-analysis and Radiological Study

BACKGROUND

The popliteofibular ligament (PFL) is a static stabilizer of the posterolateral corner of the knee, preventing varus angulation, tibial rotation, and posterior translation. The PFL is anatomically variable, and there is no current review that outlines its prevalence rate and morphological variations.

PURPOSE

To investigate the anatomic prevalence and morphological qualities of the PFL in various global patient populations via a meta-analysis of relevant literature involving both cadaveric dissections and patient-based research using magnetic resonance imaging (MRI) scans.

STUDY DESIGN

Meta-analysis.

METHODS

We pooled literature data detailing PFL prevalence rates and performed a retrospective MRI study of 100 knees to determine the overall PFL prevalence. Data searches and analyses were performed according to Anatomical Quality Assurance and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

RESULTS

There were 30 cadaveric studies and 11 MRI studies (including our radiological investigation), representing a total of 1595 lower limbs. The meta-analysis of cadaveric studies showed a higher prevalence of the PFL than the meta-analysis of MRI studies, with 98.4% (95% CI, 97.5%-99.2%) and 89.0% (95% CI, 73.9%-98.6%), respectively. Our MRI investigation reported a PFL prevalence of 92.0%.

CONCLUSION

The PFL was found to be a constant or rarely absent anatomic structure of the human knee according to the analysis of cadaveric dissection studies, and it was identified notably less on MRI, albeit not significantly. Increasing PFL anatomic knowledge, including awareness of its prevalence and morphological diversity, will improve injury diagnoses, treatment methods, and prognoses.

Editorial Commentary: Posterolateral Corner Reconstruction: Is Better (Anatomy) the Enemy of Good?

The negative consequences of neglected posterolateral corner injury (PLC) have led to numerous advancements in the understanding and treatment of these injuries. As anatomic, biomechanical, and clinical knowledge of PLC injury continues to progress, finding the balance between re-creating native anatomy and safely performing PLC reconstruction continues to provide challenges to surgeons managing this complex constellation of injuries.