Neurologic Complications following Arthroscopic & Related Sports Surgery: Prevention, Work-up and Treatment

Abstract

Arthroscopy of the shoulder, elbow, hip, and knee has become increasingly utilized due to continued advancements in technique, training, and instrumentation. Additionally, arthroscopy is generally safe and effective in the utilization of joint preservation surgical techniques. The arthroscopist must utilize a thorough understanding of the surgical anatomy, detailed care with patient positioning, and safe instrumentation portals in order to prevent associated neurologic injury. In the event of postoperative neurologic complications, the physician must carefully document the patient history and physical exam while considering the utilization of additional imaging, testing, or surgical nerve exploration with a specialized team depending upon the severity of neurologic injury. In this review, we discuss the prevention, evaluation, and treatment of neurologic complications related for arthroscopic procedures of the shoulder, elbow, hip and knee.

Introduction

Arthroscopy of the shoulder, elbow, hip, and knee has become increasingly utilized due to continued advancements in surgical technique and instrumentation. Arthroscopy is generally a safe and effective surgical technique for addressing a wide range of joint pathology. Iatrogenic peripheral nerve injury following arthroscopic surgery is rare, but may result in significant patient morbidity and possible legal action against the orthopedic surgeon. ¹ Arthroscopic related nerve injuries typically result from traction due to patient positioning, portal placement, laceration, or suture entrapment. Inherent risk factors for neurologic complications include the specific arthroscopic surgical procedure, patient position, body habitus, and arthroscopic portals. The arthroscopist must possess advanced knowledge of the potential risks and thoroughly understand of the surgical anatomy, patient positioning, and portal placement This review outlines the prevention, evaluation, and treatment of the neurologic complications associated with arthroscopic procedures of the shoulder, elbow, hip and knee.

Shoulder

Shoulder arthroscopy is one of the most commonly reported surgical procedures performed by orthopedic surgeons.² The brachial plexus and its branches (notably the axillary, suprascapular, and musculocutaneous nerves) travel in close proximity to the glenohumeral joint to provide muscular and cutaneous innervation to the shoulder and arm, placing them at risk during both open and arthroscopic shoulder procedures.^{2, 3}

Patient Positioning

Neurologic injury as the result of patient positioning in shoulder arthroscopy has been more commonly reported following utilization of the lateral decubitus position (vs. beach-chair positioning) with traction on the operative extremity and/or utilization of an anteroinferior portal.^{4, 5} Klein et al.⁶ reported strain on the brachial plexus in the lateral decubitus position as a function of both arm position and traction load, demonstrating increasing shoulder flexion to result in decreasing strain on the brachial plexus. As such, Klein et al. concluded optimal lateral decubitus position for both arthroscopic visualization and decreased strain on the brachial plexus to be at either (1) 45 degrees of forward flexion with 90 degrees of abduction or (2) 45 degrees of forward flexion and 0 degree of abduction. Excessive longitudinal traction should also be avoided (i.e. >10 lbs.). Ultimately, the amount of both abduction and flexion required for visualization remains up to debate, but is an important consideration for the arthroscopist in regards to reduction of brachial plexus strain if the lateral decubitus position is utilized.^{5, 7} Furthermore, in both the lateral decubitus and beach-chair positions, the head and cervical spine should be maintained in neutral position. Neck extension or contralateral bending will place tension on the brachial plexus and may also increase risk of iatrogenic injury.

Surgical Anatomy

The axillary nerve branches from the posterior cord (C5–6) of the brachial plexus, travels posterior to the coracoid and along the inferior border of the subscapularis before passing around the humeral neck (via the quadrilateral space) with the posterior circumflex humeral artery. It then emerges immediately adjacent to the inferior glenohumeral capsule supplying the deltoid and teres minor, with the anterior deltoid branch being located 3–7 cm from the lateral edge of the acromion.^8–10

The suprascapular nerve branches from the upper trunk (C5–6) of the brachial plexus, crosses through the posterior triangle of the neck, and travels through the suprascapular notch deep to the transverse scapular ligament. It then runs inferolateral with the suprascapular artery, providing innervation to the supraspinatus before traversing around the scapular spine to innervate the infraspinatus. At the exit of the scapular notch, it resides 2.5–4 cm medial to the supraglenoid tubercle, and at the base of the scapular spine it resides 1.5–2.5 cm from the midline of the posterior glenoid.¹¹

The musculocutaneous nerve is also at risk with open and arthroscopic shoulder surgery. It arises as the terminal branch of the lateral cord (C5–7) of the brachial plexus and travels inferior to the coracoid where it pierces the coracobrachialis muscle 3–8 cm distal to the coracoid.^{12, 13}

Portal Placement

The posterior portal is commonly created 2 cm inferior and 1–2 cm medial to the posterolateral corner of the acromion, corresponding to the “soft-spot” between the infraspinatus (suprascapular nerve) and teres minor (axillary nerve).¹⁴ Creation of this portal too inferiorly could potentially injury the axillary nerve. The suprascapular nerve has been demonstrated to be located an average of 29 mm from the posterior portal.⁹ As such, placing the portal too medial or excessively angulating the cannula medially may place the suprascapular nerve at risk.¹⁵

Placement of the anterior portal is typically created under direct visualization after establishing the posterior portal. An anterior portal can be placed anywhere in the rotator interval, but placement in a position excessively medial to the coracoid may confer risk to the musculocutaneous nerve which typically resides25 mm or more away from the anteromedial aspect of the coracoid (Figure 1).¹³

Figure 1:

Schematic portal placement and musculocutaneous nerve anatomy at the shoulder

The lateral portal used to access the subacromial space is established 1–2 cm distal to the lateral edge of the acromion, passing directly through the deltoid (Axillary nerve). As such, a standard arthroscopic incision will often pass 0.5–2.5 cm superior to the trunk of the axillary nerve.⁸ The arthroscopist must utilize caution to avoid creating the entry portal too far inferiorly or excessively angulating the cannula on insertion. However, placement of the portal too far superiorly may result in difficult access to the acromioclavicular joint during arthroscopy due to blocked visualization by the acromion.

In regards to accessory portals, a low anterior “trans-subscapularis” portal is used by some arthroscopists for anchor placement in Bankart labral repair.¹⁶ If the cannula is angled too far inferiorly, the axillary nerve may be at risk near the inferior joint capsule. The Nevasier portal is placed immediately medial to the acromion through the supraspinatus (suprascapular nerve) and is commonly utilized for superior labrum anterior and posterior (SLAP) repair. As previously noted the suprascapular nerve lies in close proximity (average of 29 mm) from the supraglenoid tubercle and may be at risk with aberrant placement. Lastly, the anterolateral (Port of Wilmington) is created slightly medial to the posterolateral corner of the acromion and is commonly utilized to repair SLAP and rotator cuff tears. In similar fashion to the other portals established in this vicinity, care must be taken to avoid injury to the axillary nerve inferiorly.

Elbow

Neurological complications have more commonly been described following open sports related procedures such as distal biceps tendon repair and ulnar collateral ligament (UCL) reconstruction. In a systematic review of distal biceps tendon repair, 13.6% of patients experienced neurologic complications, most commonly to the lateral antebrachial cutaneous nerve (LABCN).¹⁷ Although most LABCN palsies resolved, 10% persisted at final follow-up. Ulnar nerve neurapraxia is the primary complication following UCLR, occurring in up to 6.7–12.9% of patients.^{18, 19} Higher rates have been reported to be associated with the figure of eight or modified Jobe techniques in comparison to the docking technique or one of its variations, likely due to mobilization of the ulnar nerve.^18–20

Neurologic complications after elbow arthroscopy have been reported to range from 1.7–5.9% of cases.^21–26 Although major injury resulting from nerve transection during elbow arthroscopy has been described in case reports, the majority of neurologic complications following elbow arthroscopy are demonstrated to be transient and self-resolving.^{24, 27, 28} The potential for neurologic complications is greater in elbow arthroscopy than both knee or shoulder arthroscopy, largely due to the close proximity of vulnerable neurologic structures.¹⁷ Additionally, prior elbow surgery may alter the normal anatomy of the elbow and nearby neurovascular structures, with previous studies demonstrating an association between prior elbow surgery and neurologic complications.^{21, 23} However, other large case series have not supported this association.^{22, 24, 26} Destructive joint diseases (i.e. rheumatoid arthritis) also demonstrate potential to distort elbow anatomy, and arthroscopic visualization of the elbow in these patients may be complicated by extensive synovitis, requiring synovectomy.¹⁷

Patient Positioning

Prevention of intraoperative neurologic complications begins with proper patient positioning. For arthroscopy, patients may be placed in the supine, prone, or lateral decubitus positions. Ideal elbow positioning is from 80–90 degrees of flexion, which translates the brachial artery and anterior nerves furthest from the portal sites, thus decreasing risk of injury. Prior to insufflation of a tourniquet, the anatomical structures of the elbow should be identified and marked.²⁹

Surgical Anatomy

The ulnar nerve arises as a branch of the medial cord of the brachial plexus and travels along the medial aspect of the upper arm before passing posteriorly to the medial epicondyle (Figure 2). Distal to the elbow, the ulnar nerve enters the flexor compartment of the forearm and travels deep to the flexor carpi ulnaris. Large case series report the rate of ulnar nerve injury to range from 0–4.3% in elbow arthroscopy.^21–26 The majority of these injuries are transient neurapraxias; however, more serious injuries requiring re-operation and/or resulting in permanent deficits have been reported.²⁶

Figure 2:

Bony anatomy of the elbow marked out preoperatively with the ulnar nerve and portal placement overlaid. DPP – direct posterior portal; PLP – posterolateral portal; DLP – direct lateral portal; DUP – distal ulnar portal

The radial nerve is the continuation of the posterior cord of the brachial plexus. Proximal to the elbow, it passes between the brachialis and brachioradialis before crossing the elbow anterior to the lateral epicondyle (Figure 3). At the joint line, the radial nerve divides into its terminal branches: the superficial radial nerve (SRN) and the posterior interosseous nerve (PIN). The SRN supplies sensory innervation to the dorsal thumb, index, and long fingers and the radial half of the ring finger. The PIN innervates the wrist extensors in the posterior compartment of the forearm. Radial nerve palsy following elbow arthroscopy commonly involves the SRN and/or PIN.^21–26 Radial nerve palsy has been reported to occur after 0–1.2% of cases in large series.^{21, 22, 24, 25} Similar to ulnar nerve injury, the majority are transient sensory deficits, with long lasting sensory or motor deficits being far less common.

Figure 3:

Bony anatomy of the lateral elbow marked out preoperatively with the radial nerve and portal placement overlaid. PALP – proximal anterolateral portal; MALP – mid-anterolateral portal; ALP – anterolateral portal

The median nerve arises from the medial and lateral cords of the brachial plexus and travels with the brachial artery in the arm (Figure 4). It crosses the elbow through the medial portion of the cubital fossa between the pronator teres and biceps brachii tendon before continuing distally between the flexor digitorum superficialis and flexor digitorum profundus. The anterior interosseous nerve (AIN) branches from the median nerve distal to the lateral epicondyle and passes between the two heads of the pronator teres to provide motor innervation to the muscles of the deep anterior forearm. In several large series of elbow arthroscopy, median nerve or AIN injury has been reported to occur in 0–0.4% of cases, making it less commonly injured than the ulnar or radial nerves.^21–26 Permanent complications are typically only observed in instances of partial or complete transection.²⁶

Figure 4:

Bony anatomy of the medial elbow marked out preoperatively with the median and medial antebrachial cutaneous (MABCN) nerves and portal placement overlaid. PAMP – proximal anteromedial portal; MAMP – mid-anteromedial portal; AMP – anteromedial portal

Portal Placement

The majority of neurologic complications in elbow arthroscopy result from injury during portal placement.^{21, 22, 30} Prior to starting, the elbow can be insufflated with normal saline to distend the joint and increase the distance from the joint to major neurovascular structures. When establishing lateral portals, the patient’s elbow should be supinated to increase the distance between the PIN and the portal insertion site.³¹ Although posteromedial portals are generally avoided due to the normal position of the ulnar nerve, special attention must be paid to patients with prior ulnar nerve surgery or transposition. In those cases, a more extensive incision should be utilized to identify and protect the ulnar nerve prior to anteromedial portal placement.³²

Hip

Hip arthroscopy is increasingly utilized for the treatment of both intraarticular and peripheral compartment conditions as our understanding of hip pathology, development of surgical instrumentation, and techniques continue to improve. Recent studies have demonstrated approximately 250% increase in hip arthroscopic procedures between 2007–2011.³³ However, with an increase in the utilization of hip arthroscopy, there has also been an increase in complications which may compromise patient outcomes.³⁴ Specifically, the pudendal and lateral femoral cutaneous nerve (LFCN) are predisposed to injury due to traction set-up and portal placement, respectively.³⁴

Surgical Anatomy

The lateral femoral cutaneous nerve (LFCN) originates from the posterior division of the lumbar plexus (L2–3), emerges from the lateral border of the psoas major and crosses obliquely towards the anterior superior iliac spine (ASIS), passes deep to the inguinal ligament (IL) and superficial to the sartorius muscle into the thigh, where it divides into an anterior and posterior branches providing cutaneous sensory innervation to the anterolateral and lateral thigh.³⁵ The LFCN has variable anatomy, particularly with regards to exit points from the pelvis, which is typically classified relative to the ASIS. At least four common variations have been described describing the exit of LFCN from the pelvis: (1) medial to ASIS and under IL, (2) medial to ASIS and over IL, (3) directly over ASIS, and (4) lateral to ASIS.³⁵ In addition, it has a variety of branching patterns with variable branching distances from the ASIS. ³⁵

The pudendal nerve (S2–4) branches from the lumbosacral plexus and descends between the piriformis and ischiococcygeus muscles, exiting the pelvis through the inferior portion of the greater sciatic foramen.³⁵ It re-enters the pelvis through the lesser sciatic foramen and is accompanied by the pudendal artery and vein through the pudendal canal, which is formed in the fascia of the obturator internus, before dividing into branches supplying respective functions.³⁵ The pudendal nerve proper has both motor and sensory functions with additional sympathetic fibers. Pudendal nerve branches are responsible for sensation to the groin, afferent components of male and female erections, and motor function of muscles of the perineum and pelvic floor including the external anal and urethral sphincters. ³⁵

Traction Related Complications

Mechanical traction is helpful, and often necessary, when working in the central or intraarticular compartment of the hip, as it aids in providing adequate working space for instrumentation. However, traction of the hip across the groin using a perineal post poses a risk to multiple nerves, including the pudendal nerve, with complication rates reported as high as 7%.³⁶ Various factors have been proposed to increase the risk of traction related nerve injuries including, but not limited to, traction duration, traction force, excessive flexion or extension in traction. Generally, it is recommended that traction time not exceed 2 hours, and if longer traction duration is needed, it be used intermittently.³⁷ Additional risk factors for traction related neurologic injury is use of perineal post, smaller or narrower perineal post, and perineal post malposition.³⁷ Studies have shown that limiting traction duration with a well-padded perineal post of at least 9cm (or post-less hip arthroscopy) with counter traction on the contralateral leg distributes the force over a large area of the proximal thigh and ensures that the pressure is being placed through the medial thigh, and not through the groin or genitalia.^{37, 38} Additionally, muscle relaxation can also be helpful in minimizing the amount of force needed for distraction of the hip joint and adequate visualization. A recent prospective study by Welton et al.³⁹ evaluated postless hip arthrocopy and demonstrated it to be safe (zero cases of pudendal nerve injury) with muscle tissue damage which was transient, subclinical, and reduced compared to with distraction with a perineal post.

Most traction injuries in hip arthroscopy are generally transient neuropraxial injuries which resolve in minutes to hours of completion of the procedure though some may take as long as a few months.^{40, 41} When the pudendal nerve is involved, symptoms involve “saddle” anesthesia, or decreased sensation in the perineum/groin area. In addition, more severe symptoms of pudendal injury include erectile dysfunction, impotence, and urinary or fecal urgency. However, permanent dysfunction of the pudendal nerve from hip arthroscopy remains exceedingly low, especially with the use of aforementioned precautions.^{34, 41}

Portal Related Complications

Hip arthroscopy is a technical procedure which dictates portal placement near several neurovascular structures. Specifically, the LFCN is the structure closest in proximity to standard portal placement (anterior portal) due to both portal location and variable LFCN anatomy.⁴² Modified anterior or mid-anterior portal, which is placed 1–2cm lateral to the typical anterior portal, may decrease the risk of LFCN. However, it is difficult to ascertain direct decrease in risk due to the LFCNs variable branching pattern.⁴² In addition to modification of portal location, some authors recommend avoiding stab incisions and instead cutting only dermis, with blunt spreading for instrumentation, in order to avoid LFCN damage.⁴² Still, many patients report numbness in the anterolateral thigh following hip arthroscopy. The overall incidence of LFCN injury in hip arthroscopy has been reported to be between 1% and 10%⁴³, and while the most common result is temporary dysesthesia, more severe complications such as meralgia paresthetica may result.⁴⁴ While meralgia paresthetica resolves spontaneously the majority of the time, in rare instances the neurogenic pain may require anti-seizure or anti-depressant medications, and sometimes even interventional analgesic blocks or surgical intervention due to significant discomfort and disability.^{44, 45} For high-risk patients or those with predisposition (such as prior meralgia paresthetica), pre-operative ultrasound mapping of the LFCN can assist in identifying LFCN anatomy and optimize portal placement (Figure 5).

Figure 5:

Pre-operative ultrasound mapping of the LFCN in high-risk patients may assist in identifying LFCN anatomy and optimize portal placement.

Knee

Large cohort studies report overall knee arthroscopy complications to range from 0.6% to 8.2%.^{46, 47} More recent data identified knee arthroscopy surgical related complications in 3.7%.⁴⁸ Incidence of iatrogenic peripheral nerve injuries has been reported up to 0.6%, with saphenous nerve injuries being the most common.⁴⁹ These injuries are likely to be underreported in the literature. Prevention of injuries during arthroscopic and sports related surgery may be due to a direct injury to the nerve, compression from tethering sutures, tourniquet-related neurapraxia, or sympathetic dystrophy. ⁵⁰ Arthroscopic lateral meniscectomy and meniscal repair have been recognized procedures associated with risk of common and deep peroneal nerve injuries.^{51, 52}

Surgical Anatomy

The sciatic nerve originates from L4-S2 nerve roots and divides into the tibial nerve and common peroneal nerve at the popliteal fossa. The common peroneal nerve branch travels deep to the biceps femoris muscle, before crossing over the lateral head of the gastrocnemius muscle and arising subcutaneously at the level of the fibular neck where it divides the sensory articular branch, the deep peroneal and superficial peroneal nerves. The deep and superficial peroneal nerves respectfully provide motor innervation to the anterior and lateral compartments of the leg.⁵³ Other secondary sensory terminal branches of the common peroneal nerve include the lateral sural cutaneous branch, the peroneal communicating branch (communicating branch with the medial sural nerve) and the cutaneous peroneal branch.⁵⁴

The common peroneal nerve (Figure 6) has considerable variations in regards to the location of the division between the deep and superficial peroneal terminal branches. Knowledge of these anatomic variations is essential to ensure adequate neurovascular protection and localize any presumed site of injury when faced with postoperative complications. In a cadaveric study, Deutsch et al.⁵⁴ described three main variations in the anatomic location of the common peroneal nerve division. In 81% of knee cadaveric specimens the common peroneal nerve divided at or distal to the level of the fibular neck, in 10% it divided proximal to the knee joint (average of 7.5 mm proximal), and in 8% the division occurred proximally to the fibular neck (average distance of 33 mm distal to the knee joint). Along with the anatomic variability of the peroneal nerve, its superficial location at the fibular neck, low ratio of epineural to fascicular tissue, multiple tethering branches, and passage through a fibrous arcade at the fibular neck put the peroneal nerve at high risk of traumatic and iatrogenic injuries.

Figure 6:

Schematic anatomy of the Common Peroneal nerve and its branches at the lateral knee.

Although peroneal nerve injuries are uncommon, they are often related to technical errors, underuse of posterolateral incision with deflecting device, and unrecognized anatomic variations.^{47, 55} Adequate marking of anatomic landmarks before arthroscopic surgery helps localization of the lateral safe zone during lateral side exposure or portal placement. These skin markings also act as a reminder to the surgical team throughout the intervention. Common peroneal nerve proximity to the fibular neck subjects this nerve to compression injuries during surgery. Adequate padding and protection of the fibular head is essential to protect nerve related injuries of the operative and non-operative sides during surgery.

Meniscal surgery

Care should be taken when using the arthroscopic shaver in the lateral compartment. Always visualize the end of the device in order to minimize risks of extracapsular breeching and peroneal nerve injury.⁵⁰ Additionally, knee flexion allows the peroneal nerve to fall further posterior to the biceps femoris tendon, which may be a safer position during lateral meniscal surgery.⁵⁶ When performing all-inside meniscal repairs of the lateral meniscus, careful needle placement and capsular perforation are necessary. Cuellar et al. ⁵⁷ demonstrated the distance of meniscal suture devices to the peroneal nerve to increase substantially when performing repairs in deep flexion. Suturing the lateral meniscus medially to the popliteus hiatus places the popliteal vessels at more risk, especially when performing the repair from the AL portal. Suturing the lateral meniscus through the AM portal places the peroneal nerve most at risk, especially in knee extension.⁵⁸

Adequate surgical exposure of the posterolateral knee capsule is mandatory for safe inside-out meniscal repair by allowing suture passage under direct visualization. Surgical exposure is performed through the interval between the IT band and the biceps femoris at the level of the joint line. Adequate exposure should be carried anteriorly to the lateral head of the gastrocnemius with care to stay posterior to the fibular collateral ligament. The use of a retractor as a deflecting device when retrieving the inside-out suture devices allows needle visualization at the site of capsule perforation and prevents iatrogenic nerve injuries. Knot tying is performed with good suture and capsule visualization. Even with careful dissection and suture management, nerve palsy may still occur.⁵²

Portal placement

Posterolateral portal placement should be performed at 90 degrees of flexion because the safe area for portal placement increases as the peroneal nerve translates posteriorly. Safe portal placement lies in the muscular interval between the posterior border of the iliotibial band and the anterior border of the biceps femoris and posterior/proximal to the FCL, performed under direct intra-articular visualization with a localizing needle. When adequate positioning is confirmed, the needle is left in place and a vertical portal is created following the needle tract with the blade facing upwards. Capsular perforation should be completed utilizing a trochar rather than the knife blade. Use of a cannula allows easier and repeated safe access through this portal.

ACL femoral tunnel

Surgeons should also be mindful of the anatomic location of the peroneal nerve when performing arthroscopic ACL reconstruction, especially when utilizing guide pins. These pins should exit anteriorly to the posterior of the margin of the ITB band in order to limit the risk of iatrogenic injuries to peroneal nerve. When performing double bundle ACL reconstruction, the posterolateral femoral tunnel placement puts the peroneal nerve at most risk of nerve puncture. In a cadaveric study, increasing knee flexion significantly increased the distance between the guide pins and the peroneal nerve when comparing 70° of knee flexion to 120°.⁵⁹

Posterolateral Corner Exposure

Thorough understanding of the common peroneal nerve anatomy is essential when performing posterolateral corner surgery. It is essential to document nerve function in the preoperative assessment, and careful identification and exposure of the nerve will reduce the risk of iatrogenic injuries during surgery. As the normal anatomy may be disrupted following PLC injury, it is important to have access to experienced colleagues to help with difficult nerve exposure. Our preferred technique is to identify and dissect the common peroneal nerve proximally to the injury site as it travels posterior the biceps femoris tendon (Figure 7). After adequate localization, a careful exposure of the peroneal nerve is carried all the way to the fibular neck until identification of the recurrent articular branch. This extensive dissection allows for adequate and safe manipulation of the nerve when performing PLC reconstruction. Careful attention should be exercised when drilling the fibular tunnel, as the nerve is in close proximity to surgical instruments and at higher risks of iatrogenic injuries. Both Stannard et al.⁶⁰ and LaPrade et al.⁶¹ have reported a 2% iatrogenic injury rate to the peroneal nerve with PLC reconstruction.

Figure 7:

Intraoperative view of the Common peroneal nerve (vessel loop) at the lateral knee

Workup and Treatment

Postoperative nerve related complications should be carefully documented with a thorough physical examination centered on the patient’s symptoms. A careful clinical examination can help the surgeon identify the suspected location of the injury as well as the extent of injury (partial vs complete). Early signs of cutaneous nerve injuries may include vasomotor paralysis and a warm extremity or anhidrosis, which should be well documented. The clinician should also be sensitive to any signs of a compressive hematoma as an underlying cause of nerve dysfunction, or compartment syndrome, which may result in nerve dysfunction if identification and treatment is improperly delayed, and should be addressed with surgical decompression.

Radiographs may assist in identifying any suspected implant impingement in the postoperative period. More advanced imaging as ultrasound and MRI (T2 and STIR) may help the clinician identify causes for clinical symptoms of nerve injuries. Electromyography (EMG) and nerve conduction studies (NCS) also assist the clinician document the severity of the injury and help in determining the recovery prognosis. A multidisciplinary team approach is also essential in pursuit of the best clinical outcomes following arthroscopic neurologic complications. In the event of residual motor deficit, physical therapy is paramount to maintain additional strength of surrounding musculature and joint ROM. For example, in peroneal nerve injury, equinus contracture at the ankle joint is of the main concern. Physical therapy and orthotics should be utilized to maintain passive ankle ROM in the presence of dorsiflexion and eversion motor function loss. The use of ankle-foot orthotics (AFO) is supported for improved function and ROM preservation in patients with foot drop, and should be initiated early on with loss of motor function. This option is usually temporary but can also be considered as a long-term treatment option relative on patient needs and desires.

For incomplete iatrogenic lesions, observation is typically recommended for a period of up to 3 months. EMG and NCS studies may be utilized at 6 weeks at the earliest for baseline documentation. With EMG, the surgeon is able to (1) assess for any nerve activity and (2) serve as a baseline for gauging improvement in follow-up studies. If no clinical improvement is documented, a repeat EMG and NCS may be repeated at 3 months to eliminate any signs of severe conduction block or disruption of motor innervation, which may warrant surgical exploration. With any residual symptoms after 9 months of conservative management, repeat EMG and NSC are recommended to document any residual conduction block which could be addressed with neurolysis. Nerve fiber fibrosis occurs at 12–24 months after the injury, with full denervation reported to at 24 months.

If a complete nerve injury or rapidly progressive loss of motor function is noted, several things should be considered.. If nerve compression or tethering is noticed, it should be released and complete neurolysis should be performed. For acute nerve transection injury, surgical management may involve early direct repair vs. immediate surgical exploration. However, surgeons should consider the potential for additional nerve damage due to complete nerve injury due from surgical retraction, contusion, or traction with immediate exploration. As such, allowing the injury to declare itself prior to nerve exploration and repair should be considered. Functional nerve loss may also be related to traction injuries or, more commonly, traumatic injuries. Inadvertent nerve injuries related to shaving devices have also been reported, and these cases may be treated with autologous or allograft interposition surgery at the time of surgical exploration.^{50, 53, 58, 62} For example, a partial tibial nerve transfer to the tibialis anterior for treatment of traumatic peroneal nerve injuries has been described and reports excellent results in restoring the dorsiflexion strength and function after knee trauma.⁶³ However, more data is needed for the use of this technique in iatrogenic nerve injuries which tend to be less extensive than traumatic nerve injuries.

Lastly, tendon transfers may be useful to restore certain severe functional deficits. In the shoulder, for example, this may involve transfer of the trapezius muscle (spinal accessory nerve, CN XI), latissimus dorsi (thoracodorsal) and/or teres major (lower subscapular nerve) following upper trunk brachial plexus injuries to improve external rotation and abduction.⁶⁴ In the knee and common peroneal nerve deficit, this might involve transfer of the posterior tibial tendon to the lateral cuneiform in order to restore ankle dorsiflexion.

Conclusions

Arthroscopy is increasingly utilized due to advances in physician training, evolving techniques, and improved instrumentation. Neurologic injuries following arthroscopic shoulder, elbow, hip, and knee surgeries are uncommon, but the arthroscopist must possess advanced knowledge of the potential risks and thoroughly understand surgical anatomy, patient positioning, and portal placement. In the event of postoperative neurologic complications, the physician must carefully document the patient history and physical exam while considering additional imaging, testing, or surgical nerve exploration with a specialized team depending upon the severity of neurologic injury.