Case Report

Surgical Management of Peroneal Nerve Injury in Complex Sports Knee Injuries

Nath RK* and Somasundaram C
Department Brachial Plexus and Peripheral Nerve Surgery, Texas Nerve and Paralysis Institute, USA


*Corresponding author: Rahul Kumar Nath, Department Brachial Plexus and Peripheral Nerve Surgery, Texas Nerve and Paralysis Institute, 6400. Fannin st. Houston, TX- 77030, USA


Published: 21 May, 2016
Cite this article as :Nath RK, Somasundaram C. Surgical Management of Peroneal Nerve Injury in Complex Sports Knee Injuries. Clin Surg. 2016; 1: 1008.

Abstract

Objective: SOur study analyzes 6 operative knee-level peroneal nerve lesions and foot drop patients treated at our clinic.
Introduction: The most frequent lower extremity injuries resulting from sports and related recreational activities is peroneal nerve entrapment. This can be acute or can arise due to chronic overuse. Numerous etiologies have been identified. However, compression remains the main cause, which generally results in acute complete or partial foot drop.
Method and Patients: This is a retrospective study of a series of 6 consecutive patients with foot drop resulting from sports and related injuries. For all patients, the preoperative clinical examination and electromyographic evaluation were performed. Nerve conduction and clinical function results showed injury to the peroneal nerve. Peroneal nerve decompression was performed in these patients in our study between 2007 and 2014.
Results: Overall statistically significant clinical and functional improvement from pre-operative MRC grade 2.5 ± 0.8 to post-operative MRC grade 4.0 ± 0.9 (P value 0.007) was achieved. Conclusion: Results of peroneal nerve decompression in sports injury foot drop patients in our study produced remarkable clinical and functional recovery in foot anti-gravity (MRC grade 4.0) and walking gait.
Conclusion: Results of peroneal nerve decompression in sports injury foot drop patients in our study produced remarkable clinical and functional recovery in foot anti-gravity (MRC grade 4.0) and walking gait.
Keywords: Sports injuries; Peroneal nerve; Decompression; Knee injury; Foot drop

Introduction

Sports injuries to the lower limbs can be acute or can occur due to chronic overuse. The most common cause of sports injuries are gymnastics, soccer, baseball, volleyball, football and running. Peroneal nerve lesion is the most frequent and common in the lower extremities and has a worse prognosis than those in the upper extremities [1,2]. This is the third most common entrapment in the body [3] and causes antigravity weakness to the tibialis anterior muscle, resulting in foot drop.This has devastating effects on patient activities, especially their profession in athletes. Typically, such lesions are difficult to manage successfully. The method of treatment is dependent on the mechanism and degree of the nerve injury.
Predicting and achieving spontaneous recovery of peroneal nerve function can be difficult. Usually, it appears as an entrapment neuropathy and the symptoms can be improved by traditional treatments. Some of these knee and foot drop injuries are complicated and surgical exploration is necessary [4]. These may not be as easily dealt with if surgery is delayed beyond 3-4 weeks [5]. We report here the results of a retrospective analysis of surgically managed 6 patients, who had knee injuries and foot drop resulting from sports and related recreational activities.


Method and Patients

This is a retrospective study of a series of 6 consecutive patients with knee injuries and foot drop. These patients in our present study had sports-related traumatic injuries associated with football, volleyball, soccer and running. All 6 patients underwent peroneal nerve decompression, micro-neurolysis, neuroplasty with us between 2007 and 2014. For all patients, the preoperative clinical examination and electromyographic evaluation were performed. Nerve conduction and clinical function results showed injury to the peroneal nerve in all 6 patients. Preoperative duration of injury and foot drop reported by the patients was recorded (between 2 weeks and 4 months). Further patient demographics, including age, sex, mechanism and extent of the injury are provided in (Table 1). Ankle eversion, inversion and dorsiflexion, toe extension, flexion and plantar flexion were clinically evaluated by the lead author (RKN) [6] using MRC scale for muscle strength pre- operatively and at least 6 months after surgery.


Table 1

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Table 1
Grading of foot drop in patients resulting from sports injuries, who underwent peroneal nerve decompression.

Duration 1 day – 4 months; Follow-up 6 – 18 months: pre-op MRC grade 2.5 ± 0.8; post-op MRC grade 4.0 ± 0.9 (P value 0.007)

Figure 1

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Figure 1
21-year-old male patient with right peroneal nerve injury and foot drop. Fell on sand while playing beach volleyball.Upper panel, ABC: before surgery.Lower panel, DEF: after surgery (peroneal nerve decompression, microneurolysis, neuroplasty).

Statistical analysis

Statistical analysis was performed using Analyse-It plugin (Leeds, United Kingdom) for Microsoft Excel 2003 software. A P- value of < 0.05 was considered as statistically significant.


Results

Overall statistically significant clinical and functional improvement from pre-operative MRC grade 2.5 ± 0.8 to postoperative MRC grade 4.0 ± 0.9 (P value 0.007) was achieved. The improvement of the injured foot movement for each of these 6 patients is shown separately in Table 1 and Figure 1, and walking Gait in Figure 2 (from videos).
Patient 1, a 21-year old male volleyball player had an acute injury and had “0” muscle strength in MRC grade for toe extension, ankle eversion and dorsiflexion before surgery. “0” indicates no movement. EMG also indicated a complete right peroneal nerve injury. This might be the impact of the continuous physical activity (running) and there was no accident involved. EMG data confirmed the left peroneal nerve injury. Patient 3, a 28-year old female patient had external compression of left peroneal nerve resulting from a motorcycle ride. Patients 4, 5 and 6 are all male football players, had foot drop due to acute injury.
Overall, in all 5 acute injury patients (except patient # 2, chronic use), toe extension, ankle eversion and dorsiflexion (foot movement category 1) were severely damaged (mean MRC 2/5) due to peroneal nerve involvement (Table 1 and 2) when compared to the other foot movements, toe and plantar flexion and ankle inversion (tibial nerve functions, category 2), mean MRC 4/5 (Table 1 and 2). The recovery after peroneal nerve decompression was 3.5/5 and 4+/5 muscle strength in foot movements in category 1 and 2 respectively.
All 5 acute injury patients in our study had MRC grade of 4 to 5 pre-operatively, in performing ankle inversion, toe and plantar flexion in spite of their poor performance in toe extension, ankle eversion and dorsiflexion (mean MRC 2/5). This pre-operative clinical evaluation indicates that these patients did not have tibial nerve injury. Therefore, in addition to EMG data, this confirms that foot drop in these patients was caused by peroneal nerve injury.
The improvement after peroneal nerve decompression was MRC 3.5/5 from MRC 2/5 in terms of toe extension, ankle eversion and dorsiflexion in these 5 patients with acute injury, whereas tibial nerve
muscle movements such as ankle inversion, toe and plantar flexion remained the same (MRC 4+/5) after the surgery as there was no tibial nerve involvement.


Figure 2

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Figure 2
21-year-old male patient with right peroneal nerve injury and foot drop.Fell on sand while playing beach volleyball.Upper panel, walking Gait before surgery.Lower panel, walking Gait after surgery (peroneal nerve decompression,microneurolysis, neuroplasty).

Table 2

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Table 2
Peroneal and tibial nerve innervating muscles and their functions.

Discussion

Continuous physical activities such as walking, cycling or running and the high impact sports activities involving lower limbs can damage a normal joint. We [6] have previously reported the successful outcome of nerve transfer to the deep peroneal nerve in 14-foot drop patients. Among all knee injury and foot drop patients treated at our clinic between 2008 and 2014, we present here only injuries resulted from sports and related recreational activities, and who were candidates for peroneal nerve decompression. Peroneal nerve injury is a well-identified complication in and around the knee region in sports activities. Some acute and severe sports injuries have the same pattern of injury as motor vehicle accidents [5], for example, the female motorcycle rider in our present study
Though, patients benefit from nonsurgical treatments, surgical decompression has been considered for stubborn patients and those with compressive masses, acute lacerations, or severe nerve conduction changes [7]. Results of the surgical decompression and neurolysis [8,9] have been reported typically with favorable outcomes. Gosk et al. [9] demonstrated efficacy of 68.5% (61 of 89 patients) by neurolysis in lesions to lower extremities. Thoma et al. [10,11] described significant improvement of ankle dorsiflexion in 19 of 20 patients with common peroneal nerve palsies treated exclusively with peroneal nerve decompression. A strong correlation between ultimate therapeutic results and timing of the operation was reported [8,9]. Further, encouraging results were reported when the delay was not more than 8 months [8,9]. Preoperative duration of injury and foot drop reported by our patients was recorded (between 2 weeks and 4 months). Tendon and nerve transfers are used only in the setting of failed decompression or for patients with a poor prognosis for nerve recovery [6,7].


Conclusion

Overall statistically significant clinical improvement to MRC grade 4.0 ± 0.9 (P value 0.007) was achieved after peroneal nerve decompression, micro-neurolysis and neuroplasty. Functional recovery was remarkable in foot anti-gravity and walking gait in these patients.


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