A COMMON CAUSE OF LATERAL KNEE PAIN

– Written by Benjamin Ferembach, Thomas Apard, and Vincent Martinel, France, Donald Lalonde, Canada, Amir Adham Ahmad, Malaysia, and Elisabet Hagert, Qatar

INTRODUCTION

Athletes of all levels constantly strive to achieve peak performance, pushing the boundaries of their physical and mental capabilities. However, with engagement in demanding sports that place stress on the lower limbs, the reality of potential injuries emerges, including nerve-related issues such as common peroneal nerve compression. The common peroneal nerve (CPN), a branch of the sciatic nerve, plays a pivotal role in lower limb function, enabling dorsiflexion of the foot and ankle eversion. Athletes may be particularly susceptible to nerve compression due to an anatomically tight tunnel, repetitive movements, high mechanical stresses, and constant demands on their lower limbs.

Wide Awake Local Anesthesia No Tourniquet (WALANT) anesthesia has revolutionized the way orthopedic surgeries are conducted, providing athletes with the opportunity to undergo surgical procedures while remaining awake and cooperative. The principle means that the surgery is done using lidocaine anesthesia mixed with epinephrine, thus taking away the need for a tourniquet and/or sedation.  What sets WALANT apart, particularly in common peroneal nerve release surgery, is its role in enhancing surgical precision through intraoperative muscle testing. This innovative approach allows surgeons to assess muscular function in real time, make necessary adjustments during the procedure, and maximize outcomes.

UNDERSTANDING COMMON PERONEAL NERVE ENTRAPMENT IN ATHLETES

Common Peroneal Nerve Anatomy

The CPN is one of the major branches of the sciatic nerve, arising from the L4 to S2 segments of the lumbar and sacral plexus. It courses down the thigh, behind the knee, and along the lower leg, where it divides into the deep peroneal nerve and the superficial peroneal nerve.

Origin: The CPN originates as a branch of the sciatic nerve in the posterior thigh.

Course and Pathway:

Thigh: The nerve descends the posterior thigh along with the biceps femoris muscle. It runs laterally and then wraps around the neck of the fibula¹.

Knee: As it approaches the knee, it gives off several branches, including the lateral sural cutaneous nerve and the articular branches to the knee joint².

Leg: After passing around the neck of the proximal fibula², it continues its course along the fibular shaft and can be palpated in the lower leg. Here, it gives off branches to muscles like the peroneus longus and peroneus brevis, as well as sensory branches to the lateral leg and ankle.

Terminal Branches:

Deep Peroneal Nerve: This branch continues deep into the leg, running alongside the anterior tibial artery. It innervates muscles on the anterior compartment of the leg, including the tibialis anterior, extensor digitorum longus, and extensor hallucis longus.

Superficial Peroneal Nerve³: The superficial peroneal nerve courses along the lateral side of the leg, supplying the muscles of the lateral compartment (peroneus longus and peroneus brevis). It also provides sensory innervation to the skin on the dorsum of the foot and toes, except for the web space between the first and second toes, which is innervated by the deep peroneal nerve.

Function: The common peroneal nerve primarily controls the muscles of the anterior and lateral compartments of the leg. It is responsible for dorsiflexion of the foot and extension of the toes, as well as the eversion of the foot. Additionally, it plays a role in providing sensory information to parts of the leg and the dorsum of the foot.

Injury to the common peroneal nerve⁴can result in a condition known as foot drop, characterized by weakness or paralysis of the muscles responsible for dorsiflexion, leading to difficulty in lifting the front part of the foot while walking^5-7.

Individual anatomical variations can occur.

The role of the CPN in athletes

Muscle Control: The common peroneal nerve innervates several muscles in the lower leg, including those responsible for dorsiflexion of the foot and eversion of the ankle. These actions are vital for maintaining balance, stability, and precise foot placement during athletic activities⁸.

Sensory Function: The common peroneal nerve also provides sensory information from the skin of the lower leg and the dorsum (top) of the foot. This sensory input is essential for athletes to have a good sense of touch and proprioception, helping them adjust their movements and respond to various surfaces and terrain.

Athletic Movements: Athletes depend on the proper functioning of the common peroneal nerve for actions such as running⁹, cutting, jumping, and quick changes of direction. The nerve's role in controlling foot and ankle movements is critical in preventing injuries and optimizing performance.

DOUBLE CRUSH SYNDROME (DCS)

The "double crush syndrome" is a concept that describes a situation where a nerve is compressed or subjected to pressure at multiple locations along its pathway. When this occurs, nerve compression at a specific location can sensitize the nerve to other compressions along its trajectory, leading to symptoms and more severe neurological problems than if each compression were present individually.

The phenomenon of "double crush" is often associated with peripheral nerves, meaning nerves located outside the brain and spinal cord. Compressions can occur at different levels, for example, compression of the nerve at a cervical level in the spine and another compression lower down in the arm or hand.

Symptoms of the "double crush syndrome" may include pain, numbness, tingling, and muscle weakness along the course of the affected nerve. It is important to diagnose and treat the "double crush syndrome" correctly to prevent symptoms from worsening and becoming chronic. Treatment may include managing nerve compression at each site, rehabilitation, and physiotherapy to restore nerve and muscle function, as well as pain management.

In summary, the "double crush syndrome" occurs when a nerve is compressed at multiple locations along its pathway, which can result in multiple neurological symptoms and more severe problems than individual nerve compressions.

COMPRESSION POINTS FOR THE SCIATIC AND COMMON PERONEAL NERVES

The sciatic nerve and the common peroneal nerve are two important nerves of the lower limb, and they can be susceptible to compressions at multiple locations along their course. Here are the potential compression sites for each of these nerves:

Sciatic Nerve¹⁰:

Compression at the spinal column: The sciatic nerve originates in the lumbar region of the spinal column. Issues such as disc herniations or spinal stenosis can lead to compression of the nerve at its source.

Compression at the piriformis: The sciatic nerve passes under the piriformis muscle, located in the pelvic region. When the piriformis muscle is tense or contracted, it can compress the sciatic nerve, resulting in what is known as the "piriformis syndrome."

Common Peroneal Nerve¹⁰:

Compression at the head of the fibula: The common peroneal nerve wraps around the head of the fibula, located just below the knee. Compression at this level can lead to a common peroneal neuropathy, causing symptoms such as muscle weakness and sensory disturbances.

Compression at the ankle: The superficial peroneal nerve passes near the ankle, where it can be compressed by traumatic injuries, sprains, or excessive friction against bony or ligamentous structures.

Compression at other levels along the leg: Similar to the sciatic nerve, the peroneal nerves (deep and superficial¹¹) can also be compressed at various levels along the leg, resulting in diverse symptoms depending on the location of the compression¹².

CPN Entrapment in Athletes

Symptoms⁴

Pain and Discomfort: Leg, knee, or foot pain, either constant or in the form of intermittent episodes with fatigability and cramps

Numbness and Tingling: Patients may experience sensations of numbness or tingling in the area innervated by the peroneal nerve. This may include the top of the foot, the front and lateral side of the leg, or the outer edge of the foot.

Muscle Weakness: Compression of the peroneal nerve is associated muscle weakness in ankle dorsiflexion and evertion (mm. tibialis anterior and peronei, respectively), as well as big toe extension (m. extensor hallucis longus). The weakness will result in difficulty walking and climbing stairs.

Loss of Sensation: In severe cases of nerve compression, patients may completely lose sensation in the affected area.

Altered Gait: To compensate for muscle weakness or sensory issues, patients may develop an abnormal gait, increasing the risk of falls and injuries.

Muscle Atrophy: If compression persists over an extended period, it can result in muscle atrophy, meaning a reduction in the size and strength of leg and foot muscles.

Foot and Toe Mobility Issues: Some patients may have difficulty moving the foot or toes normally due to nerve compression.

The different sports in which the sciatic and peroneal nerve are most commonly entrapped are seen in table 2.

Medical history and physical exam:

Prior knee surgery or trauma is an important aspect of the medical history, as CPN compression can often occur following prior knee trauma or surgery (both arthroscopic and open).

Clinical triad

The diagnosis is clinical with Hagert’s Triad that works in every dynamic nerve entrapment:

1. Pain palpating the entrapment area (2 cm below the fibular head)
2. Loss of strength in evertors and extensor (peroneus longus ++)
3. Scratch collapse test positive

Imaging/electrophysiological studies

Electrodiagnostic studies are not mandatory, as they rarely detect a dynamic entrapment.

Ultrasound may show some changes in the area surrounding the nerve but depends on the experience of the examiner. It can be normal^13,14.

MRI can sometimes be used to confirm the diagnostic but is primarily used to search for differential diagnoses¹.

Conservative treatment

Physiotherapy and kinesiotaping may relieve symptoms in the early stages of nerve entrapment.

Ultrasound-guided steroid injection can be used but, as common peroneal nerve entrapment is a dynamic entrapment, it often offers only a temporary relief.

Prevention of the repetitive movements that may compress the nerves is also important to consider¹⁵.

WALANT Anesthesia in the Sports Context

WALANT, which stands for Wide Awake Local Anesthesia No Tourniquet, is a surgical technique characterized by several distinctive features:

Local Anesthesia: WALANT relies on the use of local anesthesia, which means that only the tissues in the surgical area are numbed, while the patient remains awake. This eliminates the need for general anesthesia or deep sedation.

No Tourniquet: Unlike many surgical procedures, WALANT does not require the use of a tourniquet to restrict blood flow. Surgeons work in a tourniquet-free environment, which can reduce certain risks associated with its use, and allows patients to remain very comfortably awake.

Intraoperative Testing: One of the most distinctive features of WALANT is intraoperative testing. Surgeons can assess muscle function and sensation in real-time during surgery, allowing them to adjust their surgical approach as needed¹⁶.

Cost and Hospitalization Time: By eliminating the need for general or regional anesthesia and a fully equipped operating room, WALANT peroneal nerve release can be performed in a minor procedure room and has the potential to reduce surgical costs and the time spent in the hospital.

Patient Benefits: WALANT can offer patients a faster recovery, less postoperative pain, and a reduced risk of side effects associated with general anesthesia.

In summary, WALANT is an innovative surgical approach that relies on the use of local anesthesia, the absence of a tourniquet, and intraoperative testing to allow surgeons to operate on patients while they remain awake. This technique offers several potential advantages for both surgeons and patients.

Pros and cons of WALANT in athlete surgery

The positive and negative aspects of WALANT are reviewed in Table 2.

SURGICAL TREATMENT OF CPN COMPRESSION

Patient Preparation: Before surgery, the patient may undergo muscle testing with a physiotherapist to record loss of muscle power in the ankle joint, for pre- and post-operative evaluation.

WALANT anesthesia: The WALANT technique involves injecting a large volume of diluted local anesthesia at least 2cm beyond anywhere there will be any dissection above the deep fascia¹⁷, 40cc of solution (18 cc lidocaine with 1/100000 epinephrine + 18cc of saline + 1.8cc of 8,4%₀ bicarbonate) is administered subcutaneously where the nerve compression is located. The bony landmark is the fibula head. A 4cm radius circle is drawn with a center located 15mm under the fibula head. This will allow the patient to remain awake during the procedure while preventing pain.

Incision: The surgeon makes a small incision (2-3cm) horizontally or obliquely, while the knee is bent 90°.

Nerve release: Once the incision is made, the fascia in front of the common peroneal nerve and just posterior to the peroneal longus muscle is identified. The fat pad is located in this area, and just posteriorly the CPN is found. Depending on the cause of compression, adhesions, scar tissue, or other structures responsible for compression may be released or removed. The deep fascia is split to fully release the nerve and its branches: deep, superficial¹⁸and recurrent.

Intraoperative testing: An important feature of surgery under WALANT is intraoperative testing. During the procedure, the surgeon can test the muscle strength in both ankle and big toe extension before and after release, as the return of power is most often seen immediately after adequate release¹⁹.

Skin closure: After the nerve release is completed and any necessary adjustments are made, the incision is closed using intracutaneous 4.0 Monocryl sutures.

Post-operative management: Following surgery, the patient is allowed immediate weight-bearing. Recovery can vary depending on the complexity of the procedure and the severity of the initial compression. We recommend that the patient reduce activity and walking until the local anesthesia has worn off (usually around 5 hours). Non-prescription painkillers (i.e. acetaminophen/ibuprofen) may required for the first 1-3 days, after which the patient should follow pain-guided healing. Simply stated, the patient avoids doing what hurts and listens to pain signals to guide extent of motion and load²⁰.

RECOVERY AND RETURN TO SPORTS

Usually, there is little to no postoperative pain.

A compressive bandage is applied for 48 hours to prevent edema and reduce the risk of hematoma.

Physiotherapy is beneficial for scar management and lymphatic drainage to reduce swelling and promote lymphatic circulation. Postoperative strength testing will show improvement in proprioception and balance, and strength symmetry is regained.

A prolonged squatting position is not allowed for the first three months as it causes compression of the nerve between the scar tissue induration and the biceps femoris.

The patient is allowed to return to play without limitation when it no longer hurts to do so.²⁰

CONCLUSION

In conclusion, surgery under WALANT (Wide Awake Local Anesthesia No Tourniquet) offers an innovative and promising approach to the release of the common peroneal nerve in athletes. This revolutionary technique allows athletes to undergo surgical procedures while remaining awake and active, preserving their athletic performance and physical condition. One of the most beneficial aspects of WALANT in this context is its crucial role in improving surgical precision through real-time intraoperative testing, enabling surgeons to adjust their procedure to maximize outcomes.

The application of WALANT to the release of the common peroneal nerve also provides advantages in terms of reducing the risks associated with general anesthesia or peridural anesthesia, faster recovery, and minimizing postoperative side effects. Athletes can thus return to their sport more quickly, reducing the impact of the recovery period on their training and performance.

Benjamin Ferembach MD¹

Thomas Apard MD, FEBSH²

Vincent Martinel MD³

Donald Lalonde MD, FRCSC⁴

Amir Adham Ahmad MD⁵

Elisabet Hagert MD PhD^6,7

Clinique de l’Alliance NCT+ , Tours, France

Ultrasound-guided hand surgery, Hôpital Privé Les Franciscaines, Versailles, France.

Groupe Orthopédie Ormeau Pyrénées ELSAN, Tarbes, France

Plastic and reconstructive surgery, Hand surgery, Saint John, Canada

Prince Court Hospital, Kuala Lumpur, Malaysia

Aspetar Orthopedic and Sports Medicine Hospital, Doha, Qatar

Karolinska Institutet, Dept of Clinical Science and Education, Stockholm, Sweden.

Contact: ben.ferembach@gmail.com

References

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