Journal of the American Academy of Orthopaedic Surgeons 130 Saphenous neuritis, also known as gonalgia paresthetica or minor causalgia, is a painful condition caused by irritation of the saphe- nous nerve that occurs in the distri- bution of the nerve. Although it has been described as an atypical form (forme fruste) of reflex sympathetic dystrophy, its symptoms are usually far less obvious than those seen in overt reflex sympathetic dystro- phy. 1 Because of its often indolent course and subtle symptoms that may mimic more common causes of medial knee pain, the condition is poorly appreciated and misunder- stood. Unrecognized saphenous neuritis can complicate a patient’s clinical presentation and treatment. For example, the individual with medial knee pain accompanied by an obvi- ous degenerative medial meniscal tear and unrecognized saphenous nerve irritation has persistent pain on the medial side of the knee after arthroscopic débridement. Although the arthroscopic débridement was appropriate treatment for the patient's meniscal symptoms, medial knee pain related to saphenous neuritis was not addressed. Therefore, un- derstanding of the anatomy of the saphenous nerve, particularly its relation to the evaluation and treat- ment of saphenous neuritis, is criti- cal. The appropriate selection of nonsurgical and surgical treatment options is based on an appreciation of the etiology and clinical course of saphenous neuritis. Anatomy Anatomic descriptions of the course of the saphenous nerve have been remarkably consistent throughout the literature. 2-5 The saphenous nerve, which is purely sensory, is the largest cutaneous branch of the femoral nerve. It travels with the superficial femoral artery and vein through the adductor canal, or Hunter’s canal, a fascial channel beginning at the apex of the femoral triangle and extending to the adduc- tor hiatus (Fig. 1). The floor of the canal is composed of the adductor magnus and longus muscles; the anterolateral border is the vastus Dr. Morganti is in private practice, The Orthopaedic and Sports Medicine Center, Annapolis, MD. Dr. McFarland is Associate Professor, Orthopaedic Surgery, Division of Sports Medicine, Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD. Dr. Cosgarea is Associate Professor of Orthopaedic Surgery, Division of Sports Medicine, Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore. Reprint requests: Dr. Cosgarea, Suite 215, 10753 Falls Road, Lutherville, MD 21093. Copyright 2002 by the American Academy of Orthopaedic Surgeons. Abstract Saphenous neuritis is a painful condition caused by either irritation or com- pression at the adductor canal or elsewhere along the course of the saphenous nerve. The condition also may be associated with surgical or nonsurgical trauma to the nerve, especially at the medial or anterior aspect of the knee. Saphenous neuritis can imitate other pathology around the knee, particularly a medial meniscal tear or osteoarthritis. Unrecognized saphenous neuritis can confuse the patient's clinical picture, complicate treatment, and compro- mise results. As an isolated entity, saphenous neuritis may appear in con- junction with other common problems, such as osteoarthritis and patello- femoral pain syndrome, and it can have an indolent and protracted course. Its clinical appearance is characterized by allodynia along the course of the saphe- nous nerve. The diagnosis is confirmed by relief of symptoms after injection of the affected area with local anesthetic. Initial treatment can include non- surgical symptomatic care, treatment of associated pathology, and diagnostic or therapeutic injections of local anesthetic. In recalcitrant cases, surgical de- compression and neurectomy are potential options. The key to treatment is prompt recognition; palpation of the saphenous nerve should be part of every routine examination of the knee. J Am Acad Orthop Surg 2002;10:130-137 Saphenous Neuritis: A Poorly Understood Cause of Medial Knee Pain Christina M. Morganti, MD, Edward G. McFarland, MD, and Andrew J. Cosgarea, MD Christina M. Morganti, MD, et al Vol 10, No 2, March/April 2002 131 medialis muscle. The roof is formed distally by a fascial band connecting the adductors with the sartorius and the vastus medialis muscles. The vessels course deep to the adductor magnus tendon at the distal aspect of the canal, which separates the vessels from the saphenous nerve in the canal and creates a safe barrier during injection of the nerve at the adductor canal. Distal to the adductor canal, the saphenous nerve divides into two main branches, the infrapatellar and sartorial branches (Fig. 2). 7,8 The in- frapatellar branch pierces the sarto- rius muscle, then courses laterally to form the infrapatellar plexus, which supplies sensation from the skin inferior and lateral to the patella. The sartorial branch exits between the sartorius and gracilis muscles, then travels distally down the medial aspect of the leg near the greater saphenous vein, supplying sensa- tion from the medial side of the calf and the dorsomedial ankle and mid- foot (Fig. 2). Hunter et al 2 studied the saphe- nous nerve in 20 cadavers and found little variation in the course of the nerve except where the infra- patellar branch exited through the sartorius, a finding consistent with those of others. 9 This variability ranged from the infrapatellar branch taking a relatively horizontal course in some specimens to its taking a nearly vertical course in others. Several authors have mapped the course of the saphenous nerve or its branches in relation to external land- marks. 3-5 Lumsden and Kalenak 3 dissected 24 lower extremities and found that the exit point of the saphenous nerve from the adductor canal was best estimated at a point approximately 7.3 cm proximal and 9.8 cm medial to the superior pole of the patella. This is a consistent and important anatomic feature; accord- ingly, injections of anesthetic into the saphenous nerve can be placed at this site of potential compression. Landmarks such as these are helpful in routine physical examination of the knee, which should include pal- pation of the saphenous nerve to rule out saphenous neuritis in pa- tients with anterior or medial knee pain. Understanding variations in the course of the nerve can minimize the potential for injury during surgery. In a study by Mochida and Kikuchi, 5 30% of cadavers had an infrapatellar branch of the saphenous nerve that coursed laterally in a relatively hori- zontal pattern before crossing the proximal tibia. The authors describe a safe zone approximately 3 cm medial to the midpatellar medial margin and 1 cm medial to the medial margin of the inferior pole of the patella, where the nerve could be avoided when planning portal placement for knee arthroscopy. Figure 1 The anatomy of the adductor canal. (Adapted with permission. 6 ) Rectus femoris Vastus lateralis Femoral artery and vein Saphenous nerve Adductor canal Sartorius (cut) Vastus medialis Gracilis Adductor longus Figure 2 The anatomic course and sensory distribution of the saphenous nerve. (Adapted with permission. 7,8 ) Illioinguinal Lateral femoral cutaneous Femoral Obturator Sartorial branch Saphenous Sural Deep peroneal Medial calcaneal Medial plantar Lateral plantar Lateral calcaneal Obturator Femoral Lateral femoral cutaneous Posterior femoral cutaneous Lateral sural cutaneous Saphenous Superficial peroneal Lateral sural cutaneous Saphenous nerve Infrapatellar branch Saphenous Neuritis Journal of the American Academy of Orthopaedic Surgeons 132 Because of the relatively transverse course of the infrapatellar branch in this zone, horizontal instead of verti- cal portals were recommended. The infrapatellar branch of the saphe- nous nerve is sectioned routinely with anterior incisions on the knee, resulting in predictable sensory loss lateral, or downstream, to the inci- sion. Arthornthurasook and Gaew-Im 4 found that the sartorial branch of the saphenous nerve emerges from the sartorius-gracilis muscle interval at an average of approximately 3.3 cm posterior to the medial femoral condyle, where it becomes subcuta- neous. Awareness of this feature is important to avoid injuring the nerve when harvesting hamstring tendons. Pathophysiology Little is known about the etiology or pathophysiology of saphenous neu- ritis. Wartenberg 9 postulated that potential causes of sensory neural- gia could include traumatic, meta- bolic, or infectious etiologies. Be- cause actual traumatic or metabolic causes had not yet been identified, Wartenberg proposed that a low- virulence infection, possibly a virus, was the most likely cause of saphe- nous neuritis. 9 Most of the literature currently available on saphenous neuritis describes either compressive or traumatic (including surgical injury) etiologies. In both situations, pain, dysesthesia, and conduction distur- bances are explained physiological- ly by the wallerian degeneration that occurs to varying degrees prox- imal and distal to the site of trauma or compression. 10 In addition, saphenous neuritis has been men- tioned as a less fulminant variant of regional pain syndrome (formerly reflex sympathetic dystrophy), a poorly understood entity. Accord- ing to Lindenfield et al, 1 psychologi- cal and systemic factors, along with a local trigger such as compression or trauma, could contribute to pain independent of sympathetic ner- vous system malfunction. At many sites along its course, the saphenous nerve is vulnerable to entrapment or trauma (Fig. 3). Because the saphenous nerve con- tains fibers from the L3 and L4 spinal segments, 10 compression at this level usually causes motor symptoms along with any sensory disturbance. Entrapment of the saphenous nerve can occur more distally, between aberrant branches of the superficial femoral artery. 11 The most commonly reported site of entrapment, however, is the dis- tal aspect of the adductor canal, where the nerve pierces the fascia between the sartorius, the vastus medialis, and the adductor magnus muscles. 12-15 Distal to the adductor canal, the sartorial branch of the saphenous nerve is vulnerable to Figure 3 Sites of entrapment of the saphenous nerve. (Adapted with permission. 10 ) Sartorius (cut) Midthigh compression by aberrant femoral vessel L3 and L4 nerve roots Vastus medialis Midline incision Adductor longus Exit of the nerve from the distal adductor canal through the fascia Sartorius (cut) Saphenous nerve Medial arthroscopy portal Medial incision Medial incision Exit of the sartorial branch between gracilis and sartorius Pes bursa Proximal tibia osteochondroma denting nerve Infrapatellar branch Descending branch of saphenous nerve Medial portal Christina M. Morganti, MD, et al Vol 10, No 2, March/April 2002 133 compression where it emerges between the sartorius and gracilis muscles to become subcutaneous. 4 Similarly, the infrapatellar branch may be compressed at its emer- gence to the subcutaneous level through the sartorius muscle. 9,10 The nerve is at highest risk for sur- gical trauma around the knee. Transection, neuroma formation, and entrapment in scar have been reported in conjunction with knee and ankle arthroscopy portals, me- dial knee incisions for open menis- cectomy or meniscal repair, and anterior knee incisions. 2,5,16,17 In addition, once it is subcutaneous, the nerve is more vulnerable to blunt trauma. Compression of the Saphenous Nerve Much of the literature on saphe- nous neuritis is in the form of case reports. Examples of compression of the nerve have been seen at virtu- ally every location along its ana- tomic course. Murayama et al 11 de- scribed surgical findings in two patients with symptoms attributed to nerve compression by vascular elements. One patient was a 13- year-old girl who at surgery was found to have compression of the saphenous nerve between the fem- oral artery, a muscular branch of the artery, and a branch of the femoral vein. The other patient, a 61-year- old woman, had compression be- tween a branch of the femoral artery and the adductor magnus tendon. Entrapment of the saphenous nerve at the outlet of the adductor canal has been described in several case studies. 12-15 In 1960, Kopell and Thompson 12 reported two cases of saphenous neuritis characterized by activity-related pain as well as rest pain. The pain was most pro- nounced at the joint line and was associated with hypesthesia or hy- peresthesia along the medial side of the knee. A positive Tinel sign was noted at the adductor canal, and tem- porary relief of pain was achieved after corticosteroid injection in this area. Neither patient had a history of trauma. Both patients experi- enced relief after surgical release of the subsartorial fascia at the emer- gence of the saphenous nerve from the adductor canal. Romanoff et al 14 studied 30 pa- tients who had been previously diagnosed with saphenous nerve entrapment at the adductor canal. These patients had anterior knee pain (90%), medial thigh pain (7%), and medial calf pain (3%), normal motor function, and tenderness to palpation over the adductor canal. Average duration of symptoms was 36 months, with 70% of pa- tients requiring anti-inflammatory medication with or without antide- pressants, 10% requiring narcotics, and 20% requiring no medication. Only 27% recalled an antecedent trauma, and 6% experienced pain after surgery. Eleven of 27 patients with knee pain had undergone ar- throscopy, which was normal in all cases. Mozes et al 13 noted that the symp- toms of saphenous neuritis caused by compression in the adductor canal are similar to those of chronic venous insufficiency. They de- scribed 32 patients with saphenous neuritis. Symptoms included per- sistent pain in the lower thigh and leg; pain aggravated by walking, sometimes simulating intermittent claudication; and sensations of fatigue and heaviness in the leg. Pain was worsened with hyperex- tension of the knee in some patients. However, tenderness to palpation over the adductor canal and tran- sient relief after injection there were features that reportedly distin- guished saphenous neuritis from chronic venous insufficiency. Fabian et al 18 described an entity in two patients, termed surfer’s knee, defined as numbness and pares- thesias over the anteromedial leg below the knee. The condition is so named because it appeared in sur- fers who often sat in the water with the surfboard clenched between their knees while waiting for a wave. It was suggested that com- pression of the saphenous nerve by the surfboard at the medial knee was responsible for the leg symp- toms. Compression of the sartorial branch of the saphenous nerve has been reported at the level of the pes anserinus bursa. In a case report by Hemler et al, 19 a 30-year-old woman with this pathology had medial leg pain that persisted even after treat- ment for shin splints; work-up for stress fracture was negative. Subse- quent nerve conduction studies demonstrated slowing of saphenous nerve conduction in the pes anseri- nus region, believed to be secondary to compression of the sartorial branch of the saphenous nerve by the inflamed bursa. Relief was pro- vided by activity modification, in- jection with betamethasone with 1% lidocaine without epinephrine of the pes anserinus bursa at the point of maximum tenderness of the nerve, and ultrasound treatments. Compression caused by the pres- ence of soft-tissue and bony tumors around the knee may cause saphe- nous neuritis. An osteochondroma of the proximal tibia may irritate or stretch the overlying saphenous nerve (Fig. 4). A midthigh soft-tis- sue mass in the vicinity of the nerve was described by Edwards et al. 20 The patient had a 6-year history of anterior knee pain that worsened when a child or a book was placed on the lap, a condition later dubbed the “lap sign.” The patient’s symp- toms responded temporarily to a saphenous nerve block at the distal aspect of the adductor canal. Mag- netic resonance imaging revealed a soft-tissue mass in the midthigh region believed to be compressing the saphenous nerve. The mass, a neurilemoma, was found at surgery to be encapsulated and easily sepa- Saphenous Neuritis Journal of the American Academy of Orthopaedic Surgeons 134 rated from the nerve. Removal of the mass provided relief. Trauma to the Saphenous Nerve Saphenous neuritis may be caused by surgical trauma. It has been de- scribed as a complication associated with varicose vein stripping, saphe- nous vein graft harvesting for by- pass surgery, superficial femoral artery thromboendarterectomy, and patient positioning with leg stirrups. Saphenous neuritis also has been reported in patients who have un- dergone femoropopliteal bypass surgery. In these reports, saphenous neuritis is mentioned only briefly, without detailed descriptions of diagnostic criteria, treatment, or out- come. 21,22 Trauma to the saphenous nerve has been reported during orthopae- dic surgical procedures such as knee and ankle arthroscopy, medial ankle incisions, open meniscectomy, and anterior knee incisions for arthro- plasty or patellar realignment. 2,5,15,23 Logue and Drez 23 described a der- matitis and partial anesthesia in the distribution of the saphenous nerve after arthroscopic débridement of a medial meniscal cyst. Mochida and Kikuchi 5 found that 22% of patients undergoing arthroscopy from 1990 to 1991 experienced sensory distur- bance of the saphenous nerve after surgery, resulting in a relatively high incidence of saphenous nerve injury compared with previous sur- veys. 16 Nevertheless, the most com- monly injured nerve in knee ar- throscopy is the saphenous nerve and its branches. 17 Hunter et al 2 studied 75 patients who underwent open medial meniscectomy through a medial parapatellar incision, a procedure in which the infrapatellar branch of the saphenous nerve was routinely sectioned. Forty-seven patients reported nonincapacitating irritation, especially when kneeling, and five patients could not kneel because of paresthesia. Only 10% of 67 patients reported that the abnor- mal area of sensation had decreased after 1 year. In a study of saphe- nous nerve entrapment by Worth et al, 15 10 of 15 patients had under- gone a prior orthopaedic procedure. Blunt trauma to the anterior knee may cause neuritis of the infrapatel- lar branch of the saphenous nerve. Gordon 24 described trauma-related pain at the anterior aspect of the knee and proposed that the etiology was irritation of the nerves of the prepatellar bursa plexus. Excision of the prepatellar bursa caused the symptoms to resolve, but Warten- berg 9 subsequently suggested that Gordon’s procedure may have essentially been a neurectomy of the infrapatellar branch, which would have made the lesion he described a form of saphenous neuritis charac- terized by anterior knee pain. Poehling et al 25 retrospectively reviewed 57 patients with persistent pain about the knee. Thirty-five of these patients had histories of isolat- ed insult to the infrapatellar branch of the saphenous nerve caused by contusion, fracture, or surgery. Thirty-three of the 35 patients re- sponded to treatment for reflex sympathetic dystrophy using one or more vasoactive therapies. This is the only study that has demonstrated with physiologic testing an asso- ciation between dystrophic changes about the knee and saphenous neu- ritis. Although no cause-and-effect relationship between saphenous nerve trauma and reflex sympathet- ic dystrophy was established in this study, surgical trauma to the saphe- nous nerve has been alluded to as a form of reflex sympathetic dystro- phy of the knee in other studies. 1,26 Vascular Etiolgy Balaji and DeWeese 27 studied three patients with acute thrombosis of the femoral artery in the adductor canal who had evidence of com- pression of the artery by tendinous bands emanating from the vastus medialis and adductor magnus muscles, a condition they called jog- ger’s syndrome because two of the affected patients were joggers. Along with the signs and symptoms associated with claudication, symp- toms of numbness, tingling, and hypesthesia were documented and attributed to ischemic neuritis of the saphenous nerve. Jogger’s syndrome and saphe- nous nerve entrapment at the adductor canal should not be con- fused with adductor canal syn- drome. Lee et al 28 described this condition, a compression syndrome in which the superficial femoral artery was compressed beneath a tendinous band of the adductor magnus muscle. Because of its close proximity to the saphenous nerve in the adductor canal, the superficial femoral artery can be entrapped in a similar fashion to the nerve. Ac- cording to Lee et al, return of flow Figure 4 Anteroposterior radiograph of the proximal tibia in a 39-year-old woman. She initially had medial knee and leg pain after a fall, during which she twisted her knee. Her pain resolved with nonoperative care but recurred after a second fall. She then had burning pain with stair climbing and prolonged sitting, and had to sleep with a pillow between her legs. She was tender over the bony prominence, and her MRI was negative for intra-articular pathology. When the osteochondroma (arrow) was excised, the nerve was found to be tented over it. Christina M. Morganti, MD, et al Vol 10, No 2, March/April 2002 135 through the vessel and relief of clau- dication symptoms were obtained after transfer of the tendon 2 cm proximally. However, no mention was made of knee pain, paresthe- sias, or the condition of the saphe- nous nerve at surgery. Diagnosis History Saphenous neuritis is character- ized by pain on the medial side of the thigh, knee, or calf. The pain has been described as dull and achy, with an electric shock-like or burn- ing sensation. Often the pain is lo- cated primarily at the medial joint line and may radiate proximally or distally. Sometimes sensitivity of the affected area goes unnoticed until something comes into direct contact with the skin, such as when the medial leg is rubbed against the bedsheets when the patient gets into bed. 12 Some patients sleep with a pillow between their legs to avoid pressure on the insides of their knees. Patients often report exacerbation of symptoms while walking, sitting, or climbing stairs. The pain can be positional, sometimes occurring only while something is resting on the patient’s lap (the lap sign). 20 Patients may not experience subjec- tive sensory disturbance in the saphenous nerve distribution if the etiology of the neuritis is compres- sion. Sensory loss is usually associ- ated with saphenous neuritis from traumatic laceration of the nerve. 10 Physical Examination The hallmark of saphenous neuri- tis is tenderness to light palpation along the course of the nerve. Tenderness may be apparent any- where along the course of the nerve but most frequently is either at the nerve’s exit from the adductor canal, near the medial joint line, or along the nerve in the proximal third of the leg. A positive Tinel sign may be elicited at the point of entrapment of the nerve. Starting at the level of the nerve’s exit from the adductor canal and working progressively distal, it is frequently possible to elicit the exact course of the irritated saphenous nerve. With the patient supine, light palpation of the skin is initi- ated just anterior to the anticipated location of the nerve and is contin- ued in a posterior direction until pain is elicited. This point is noted, and anterior-to-posterior palpation is continued sequentially along the length of the leg. Allodynia that fol- lows the course of the saphenous nerve is mapped out in this way. Although saphenous neuritis has been described as an atypical form of reflex sympathetic dystrophy, the dystrophic skin changes associated with reflex sympathetic dystrophy, such as mottling and temperature difference compared with the unaf- fected limb, are conditions not com- monly seen with saphenous neuri- tis. 1 Motor examination and reflexes are normal because the nerve is purely sensory in nature. Hypes- thesia in the distribution of the saphenous nerve may be noted dur- ing testing, even if this symptom had not been apparent before. The nerve stretch test is positive when pain is present with passive, brisk stretching of the nerve. 9 Re- turning the limb to a resting posi- tion leads to resolution of pain symptoms. Passive stretching of the saphenous nerve is done with either extension or flexion, external rota- tion, and valgus stress to the knee. Provocative maneuvers used in the clinical diagnosis of medial menis- cus tears, such as McMurray’s test or the flexion circumduction test, replicate this nerve stretch test and may confuse the examiner. The diagnosis of saphenous neu- ritis can be confirmed with a nerve block, which usually is done at the level of the adductor canal. 3 Typi- cally, a short-acting local anesthetic such as lidocaine is used, although corticosteroid injection has been a favorable alternative. If sensitivity to palpation along the course of the saphenous nerve is relieved with the injection, the diagnosis of saphe- nous neuritis is confirmed. Hemler et al 19 described the use of nerve conduction studies to con- firm the diagnosis of saphenous neuritis. Decreased conduction of the saphenous nerve was found at the level of an inflamed pes anseri- nus bursa. However, the saphenous nerve is difficult to analyze using nerve conduction studies, especially in patients with large amounts of subcutaneous fat; 10 therefore, no studies have clearly identified the usefulness of nerve conduction stud- ies for confirming this diagnosis. Treatment Nonsurgical Treatment Treatment options include both nonsurgical and surgical modali- ties; however, little data exist to verify their efficacy. In fact, no studies document the use of non- surgical care for saphenous neuri- tis. Anti-inflammatory medica- tions, capsaicin cream, physical therapy, and transcutaneous elec- trical nerve stimulation (TENS) units have been discussed in the treatment of reflex sympathetic dystrophy. 1 A 6-month trial of desensitization therapy, TENS units, and, occasionally, antidepres- sant agents has been recommended for neuroma pain. 29 In a critical review of clinical trials for periph- eral neuropathic pain and regional pain syndromes, tricyclic antide- pressants were recommended as a first-line drug for treatment of all neuropathic pain, producing anal- gesic effects independent of the antidepressant effect of these drugs. 30 They are usually initiated at a dose of 10 to 25 mg nightly but Saphenous Neuritis Journal of the American Academy of Orthopaedic Surgeons 136 can be increased weekly to a maxi- mum of 150 mg per day. Depend- ing on the series, tricyclic antide- pressants were either ineffective or not well tolerated in 7% to 58% of patients. 30 Several authors have reported on diagnostic and therapeutic injec- tion for entrapment of the saphe- nous nerve at its exit from the adductor canal. 13-15 The injection is usually performed at the point ap- proximately 7.3 cm proximal and 9.8 cm medial to the superior pole of the patella, in the interval be- tween the sartorius and the vastus medialis muscles. 3 A 1.5-inch nee- dle is inserted perpendicular to the skin; a “pop” can be felt as the nee- dle pierces the fascia of the vastus medialis and enters the adductor canal. After aspiration to assure that the femoral vessels have not been penetrated, the space is infiltrated. Romanoff et al 14 reported an 80% success rate after a series of injec- tions of anesthetic in 30 patients. The adductor canal was injected with 9 mL of 0.25% bupivacaine hydrochloride and 1 mL of triamcin- olone diacetate (25 mg) at 3- to 4- week intervals, with an average 1.9 injections per patient. Perceived pain, measured with a visual analog scale in which zero was no pain and 10 was the worst pain the patient had experienced, decreased from 6.4 to 2.8 at an average 4-month follow- up. More frequently, however, re- sults after injection have been disap- pointing. Worth et al 15 described suboptimal results. Injection treat- ment failed in all patients in their study and surgical treatment was necessary. Both of the patients in the study by Kopell and Thomp- son 12 experienced only 3 to 4 days of relief after injection with hydro- cortisone. Mozes et al 13 reported success with serial injections of pro- caine hydrochloride in only 12 of 32 patients. Because no objective crite- ria were used in diagnosing these patients, and because there fre- quently was no subdivision of pa- tients into groups based on etiology, it is difficult to determine whether injection is efficacious in different subpopulations of patients with saphenous neuritis. Surgical Treatment Surgical options include neuroly- sis, decompression, and neurecto- my. Because patients are left with a permanent sensory deficit after neurectomy, decompression often is attempted preferentially. Although decompression of the saphenous nerve at the adductor canal has been described for saphenous nerve entrapment, most studies are limited, lacking good objective criteria and long-term follow-up. Worth et al 15 studied 15 cases of saphenous nerve entrapment in 14 patients, 10 of whom developed symptoms after surgery. Four of eight patients who underwent ad- ductor canal decompression had complete pain relief at follow-up of 30 months. Three patients in whom release failed underwent neurecto- my along with seven others who had primary neurectomy. Of these 10, 8 had complete relief of their symptoms. Both patients in the study by Koppel and Thompson 12 had relief of symptoms within 24 hours after decompression, but they were not followed up for longer than 2 months. Luerrsen et al 31 de- compressed the saphenous nerve in six patients, but three had subse- quent neurectomy that resulted in 100% relief of pain and the expected residual sensory deficit. Dellon et al 32 reported results of neurectomy for 70 patients who had persistent pain after total knee re- placement, trauma, or osteotomy. Sixty-two patients underwent resec- tion of the infrapatellar branch of the saphenous nerve. Eighty-four per- cent of these patients demonstrated improvement in pain as measured by visual analog scale; 68% showed improvement in the Knee Society Questionnaire score. Most of these patients underwent denervation of two or more nerves; an isolated study of denervation of the saphe- nous nerve was not performed. Summary Because of its subtle clinical picture, saphenous neuritis is easy to over- look. The most consistent features include sensitivity to light touch along the nerve; pain most frequent- ly located at the medial knee near the joint line; pain that may radiate proximally or distally; variable sen- sory deficits; pain with passive stretch of the nerve; protracted course, sometimes lasting years; concomitant patellofemoral pain; concomitant degenerative medial compartment; frequent history of failed surgery for medial knee pain; and the possible presence of surgical scars in the vicinity of the nerve associated with a sensory deficit. Saphenous neuritis can develop after trauma that often is related to surgery. Spontaneous cases occur secondary to compression of the nerve at the adductor canal, the pes anserinus bursa, tumor, or aberrant vasculature or fascial structures. The diagnosis of saphenous neuritis should be considered in patients with intractable knee pain, patients with knee pain without identifiable cause on routine imaging studies or physical examination, and patients in whom nonsurgical intervention has been unsuccessful. Unlike iso- lated saphenous neuritis, trauma- associated saphenous neuritis is usually just one component of a triad of symptoms, including medial compartment pathology, patello- femoral symptoms, and saphenous neuritis. The key to treatment is prompt recognition; palpation of the saphenous nerve should be part of every routine examination of the knee. Christina M. Morganti, MD, et al Vol 10, No 2, March/April 2002 137 Although many studies describe saphenous neuritis, its pathophysi- ology, etiology, and natural course are not well defined. None of the numerous options for treatment has been critically analyzed for effec- tiveness. However, a systematic approach beginning with nonsurgi- cal care seems most appropriate. Nonsurgical treatment of saphenous neuritis may include activity modi- fication; oral analgesics, including nonsteroidal anti-inflammatory medication and narcotics; protective padding; topical analgesic cream containing capsaicin; systemic med- ications, such as tricyclic antidepres- sants; and treatment of concomitant pathologies (eg, physical therapy for patellofemoral pain syndrome). Symptoms may subside with time, particularly if associated pathologies such as patellofemoral pain are addressed. If symptoms persist, injection of local anesthetic, without cortico- steroid, can be initiated. If tempo- rary or partial relief is obtained after injection, a second injection 3 to 4 weeks later with corticosteroid may be warranted. If nonsurgical ther- apy, including injection, fails, surgi- cal intervention by decompression or neuroma excision may follow. Neurectomy may be used if decom- pression is unsuccessful. References 1. Lindenfeld TN, Bach BR Jr, Wojtys EM: Reflex sympathetic dystrophy and pain dysfunction in the lower extremity. J Bone Joint Surg Am 1996; 78:1936-1944. 2. Hunter LY, Louis DS, Ricciardi JR, O'Connor GA: The saphenous nerve: Its course and importance in medial arthrotomy. Am J Sports Med 1979;7: 227-230. 3. Lumsden DB, Kalenak A: The saphe- nous nerve: An external method for identifying its exit from the adductor canal. Orthop Rev 1993;22:451-455. 4. Arthornthurasook A, Gaew-Im K: The sartorial nerve: Its relationship to the medial aspect of the knee. Am J Sports Med 1990;18:41-42. 5. Mochida H, Kikuchi S: Injury to infra- patellar branch of saphenous nerve in arthroscopic knee surgery. Clin Orthop 1995;320:88-94. 6. DeLee JC, Drez D: Orthopaedic Sports Medicine: Principles and Practice. 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Relief was pro- vided by activity modification, in- jection with betamethasone with 1% lidocaine without epinephrine of the pes anserinus bursa at the point of maximum tenderness of the nerve,. and symptoms associated with claudication, symp- toms of numbness, tingling, and hypesthesia were documented and attributed to ischemic neuritis of the saphenous nerve. Jogger’s syndrome and saphe- nous. done at the level of the adductor canal. 3 Typi- cally, a short-acting local anesthetic such as lidocaine is used, although corticosteroid injection has been a favorable alternative. If sensitivity to