1 Introduction

The peroneal nerve represents an “at-risk” structure during operative treatment of tibial plateau fractures (TPFs).^1,2 While the nerve is rarely visualized or manipulated during the standard anterolateral approach to the proximal tibia, recent evidence suggests that intraoperative distraction with a lateral femoral distractor (LFD) may result in an unacceptably high rate of iatrogenic injury.¹ Distraction is necessary to adequately visualize the articular surface of the tibial plateau. In cases where a previously placed external fixator is not adequate, the use of a LFD is required. The LFD should be used in any TPF where there is known or suspected articular incongruity in the lateral compartment of the knee. Radiographic interpretation alone is typically unreliable so even in “simple” isolated split fractures, direct visualization is often required. This need for anatomic reduction of the weight bearing articular surface is well documented in the literature.^3–7

Pattyn et al. in a 2020 retrospective review reported an incidence of iatrogenic peroneal nerve injury of 16.4% with the use of intraoperative LFD.¹ While this incidence may seem high, it highlights a serious issue with regards to the operative management of TPFs, as distraction is typically necessary to adequately assess the articular reduction.^2–8 Lateral distraction with a bone distractor is used in a significant percentage of plateau fracture surgeries. As such, Chen et al. performed a follow-up assessment to validate these findings and only found a 2% incidence of peroneal nerve palsy, all of which were incomplete sensory deficits.²

The goal of our study was to evaluate our experience with bone distractor assisted open reduction internal fixation (ORIF) of TPF and quantify the incidence of iatrogenic peroneal nerve palsy.^1,2 We hypothesis that there will be a low incidence of iatrogenic peroneal nerve palsy after ORIF of TPF at our institution.

2 Level of evidence: III prognostic study

2.1

2.1 Methods and materials

After institutional review board approval, we retrospectively evaluated all patients undergoing ORIF for a TPF between 2014 and 2019 (CPT 27535 and 27536). Representative pre and postoperative radiographs can be seen in Figs. 1 and 2. All procedures were performed by a single fellowship trained orthopaedic traumatologist at a single Level 1 trauma center. Inclusion criteria included the documented use of a LFD during an ORIF of a TPF. Exclusion criteria included documented preoperative neurovascular injury compromising motor or sensory function in the operative extremity. Also excluded were patients who had intraoperative distraction applied via a pre-existing knee spanning external fixator that was placed at a prior index temporizing procedure.

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Fig. 1 Pre-operative anteroposterior and lateral radiographs.

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Fig. 2 Post-operartive anteroposterior and lateral radiographs.

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Electronic medical record review was employed to gather standard demographic variables, intraoperative techniques, and postoperative outcomes. All fractures were classified according to the 1979 Schatzker classification system for tibial plateau fractures. Preoperative nerve blocks were not used in this cohort of patients and the treating surgeon does not use a tourniquet. Peroneal nerve status was based on documented clinical exams in the pre and postoperative setting. Peroneal injury was classified as complete, no motor or sensory function in the superficial (SPN) or deep (DPN) peroneal nerve distributions, or incomplete. Incomplete injuries were subsequently classified as sensory or motor, based on whether the SPN or DPN sensory distribution was involved and whether the extensor hallucis longus or tibialis anterior were involved.

3 Surgical technique

Patients were positioned supine on a standard radiolucent operating room table. A foam positioning ramp was positioned under the ipsilateral leg to elevate the extremity relative to the contralateral side to aid in fluoroscopic assessment. A standard anterolateral approach was made to the proximal tibia. A curvilinear incision is made from the thigh laterally at the level of the lateral femoral epicondyle, over Gerdy's tubercle, continuing approximately 1–2 cm lateral to the tibial crest distally. The fibers of the fascia lata are then incised longitudinally staying superficial to the lateral capsule. The fascial incision continues distally over the anterior compartment, one cm lateral to the tibial crest. The common fibers of the fascial layer are then elevated subperiosteally at Gerdy's tubercle, both anteriorly and posteriorly. The anterior compartment muscle is reflected off the anterolateral tibia. A submeniscal arthrotomy is then performed and several non-absorbable sutures are placed in the capsule for proximal retraction and articular visualization. If the lateral meniscus is traumatically detached from the lateral capsule, the sutures are passed through both the capsule and the lateral third of the meniscus, so that both can be retracted, and the meniscus is repaired to the capsule during closure. A large bone distractor (DuPuy Synthes, West Chester, PA), often referred to as a “Large Femoral Retractor” (LFR) is applied utilizing 5.0 mm Schanz screws placed in the femur at the level of the epicondyles, and the tibial shaft, distal to the anticipated plate placement. Distraction is then applied, and force is fine-tuned until articular visualization is deemed appropriate, and the fracture can be anatomically reduced. Representative intraoperative fluoroscopic radiographs can be seen in Fig. 3.

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Fig. 3 Fluoroscopic radiograph of intraoperative distraction.

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4 Results

Over a five-year period, 303 patients were identified who underwent ORIF for a tibial plateau fracture. Of these procedures, femoral distraction was used in 254 (83.8%) of these cases. Of these 254 cases, 201 had an intraoperative femoral distraction applied and the remaining 53 utilized a pre-existing knee spanning external fixator for distraction. Three patients of the remaining 178 had a documented preoperative sensory peroneal nerve palsy, including one that was diagnosed and treated for a compartment syndrome in the ipsilateral leg. In total, 175 patients met inclusion criteria.

The demographic variables for this cohort can be seen in Table 1. Two patients had open fractures. 16 patients underwent staged procedures after initial placement of a spanning external fixator. Fracture classification can also be seen in Table 1. The most common fracture type was the Schatzker 2 (Lateral Split Depression) (n = 130).

Zero patients in our study developed a complete or incomplete peroneal nerve palsy following lateral femoral distractor assisted ORIF of a TPF. Mean operative time was 117 min.

5 Discussion

Unlike the retrospective analysis performed by Pattyn et al. that prompted this evaluation, our study found no incidence of postoperative peroneal nerve palsy following intraoperative utilization of a LFD during an ORIF of a TPF.¹ This validated the hypothesis of our study that there would be a low rate of peroneal nerve palsy for ORIF of TPF at our institution. Zero patients out of the 175 included our analysis developed an incomplete or complete peroneal nerve palsy, regardless of whether they underwent a staged procedure with an initial external fixator. With that being said, the results of our study are like those of Chen et al. Their study found a 2.0% incidence of peroneal nerve palsy following bone distractor assisted ORIF of tibial plateau fractures.²

While it is unclear why there is such a difference in the incidence of this postoperative complication between the studies presented above, several possibilities exist. First, while only 175 patients met our studies inclusion criteria, over the course of five years at our institution a total of 303 patients underwent ORIF for TPFs, which represents a significant difference between the 124 patients that were identified over a 10-year period in the study performed by Pattyn et al.¹ While other variations in surgical technique may account for the significant difference in post-operative nerve palsy, it is possible that this is related to surgical volume as well as other differences in technique. As in other conditions, it may be that high volume surgeons and centers who treat conditions in higher volume are associated with improved patient outcomes.^9,10 In multiple studies evaluating outcomes in total hip arthroplasty and in hip fractures, low-volume institutions were consistently found to have higher postoperative complications and higher in-hospital mortality relative to high-volume institutions.^9–12 As the peroneal nerve is relatively fixed at the fibular neck, traction injury may occur if care is not taken to minimize varus and hyperextension forces applied to the knee. Other risk factors associated with iatrogenic peroneal palsy include female gender, constrictive dressings, compression from hematomas, higher BMI, prior spinal pathology, duration of anesthetic agents greater than 2 h.^13–16

As another example of differences in technique that may lead to a different incidence of post-operative nerve palsy, none of our cases were done with tourniquet. Nerve injury can occur via direct perioperative traction, direct compression, or traction on the surrounding soft tissue leading to vascular compromise and neural ischemia.^15–17 While it is well documented that a lower extremity tourniquet may cause direct neural injury from mechanical compression and/or hypoperfusion, it is also possible that in the case of lateral distraction, the tourniquet may act as tether for the nerve, predisposing it to a traction injury.¹⁸ Furthermore, it is generally accepted that nerve injury may often be the result of a “double hit” phenomenon, whereby the net effect of both a compression/hypoperfusion and stretch can lead to a clinically evident nerve palsy.

There are several limitations associated with this retrospective study design. First and foremost are the inherent biases and deficiencies associated with the study design itself. Further, longer duration of intra-operative distraction can affect the incidence of peroneal palsy.¹ The duration of distraction was not noted in our institution's clinical documentation. It is reasonable to assume that longer duration of traction may represent a higher risk for peroneal stretch palsy and as such those surgeons who are not as facile with performing these procedures due to limited exposure may be subject to higher rates of nerve injury. Similarly, the force and length of distraction were not standardized across patients. These variables challenge the general applicability of our findings. Lastly, while our analysis did not highlight specific fracture patterns that are more or less amenable to adequate distraction via a pre-existing external, this represents an interesting area of study that has the potential to optimize operating room efficiency.

6 Conclusion

This study supports the utilization of lateral distraction using a mechanical distractor for articular visualization and reduction during ORIF of tibial plateau fractures. Further comparative studies evaluating length and amount of distraction in the setting of a tourniquet may be useful for quantifying why there is a such a discrepancy between the reported incidence of these injuries. However, it is important to recognize that even in the absence of controlling for these variables, we saw no incidence of peroneal nerve palsy when using lateral joint distraction in treating a large number of tibial plateau fractures. This study emphasizes that lateral distraction with a mechanical distractor in performing ORIF of tibial plateau fractures is safe, with a low risk of peroneal nerve injury when performed without the use of a tourniquet.

Conflict of interest

None.

Funding/sponsorship

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Institutional Ethical Committee Approval

Institutional Ethical Committee Approval was obtained for retrospective chart review prior to beginning this study.

Authors contribution

Taylor Paziuk: Conceptualization, writing- original draft preparation; Ryan Sutton: Methodology, writing-review and editing, data curation; Richard McEntee: Methodology, data curation; Dominic Farronato: data curation; James Krieg: Supervision, writing-review and editing.