peroneal nerve entrapment is the most frequent nerve entrapment in the lower extremities and the third most common entrapment in the body , following the median and ulnar nerves . peroneal neuropathies often develop after trauma , direct injury or upon entrapment during the course of the nerve proximal or distal to the fibular head . mechanical entrapment by an osteochondroma in this anatomic region is a rare occurrence . in this study , five patients with a drop foot resulting from osteochondroma of the proximal fibula who did not receive a proper diagnosis in neurosurgery and physical therapy clinics are presented . a 2.5-year - old boy presented to the neurosurgery clinic with the complaint of limping that started shortly after beginning to walk . his neurologic background history and examination included cranial and comprehensive spinal mri for embolisms and congenital anomalies . all test results were negative for etiologic factors and the patient was referred to a physical therapy and rehabilitation clinic for six months . during the physical examination , simple gait analysis revealed missing dorsiflexion of the right foot . according to the medical research council ( mrc ) scale , further radiologic evaluation by plain x - rays , computerized tomography ( ct ) and magnetic resonance imaging ( mri ) displayed a posterolateral exostosis on the fibular neck ( fig . 1 ) . surgery was performed , and an osteochondroma , including its cartilage cap , was removed . pathologic examination revealed an osteochondroma with a thin , 2-mm cartilage cap . in the early post - operative period , electrostimulation and active and passive range of motion ( rom ) exercises were initiated . within three months following surgery , full recovery of motor functions was observed . one year after surgery , electromyogram results indicated normal excitations , and recurrence of the tumor was not noted ( table 1 ) . a 15-year - old boy presented to the physical therapy and rehabilitation center ( ptrc ) complaining of inability to dorsiflex his left toe for five months . no improvement was detected with vigorous ptrc ; therefore , the patient was referred to a neurosurgery clinic , where spinal mri studies were conducted . no improvement of the condition was observed , and the patient was referred to our department . the patient was examined , and dorsiflexion of the ankle and toe was determined as mrc grade 1 without any sensory deficit . radiologic assessment detected compression of the peroneal nerve due to an osteochondroma of the proximal fibula and fatty degeneration of the proximal musculotendiosis area of extensor hallucis longus . hourglass constriction of the peroneal truncus at the level of the fibular neck by an osteochondroma was observed . pathologic specimens depicted an osteochondroma . within the first 24  h following the surgery , electrical stimulation , accompanying active and passive range of motion exercises , was started . at the end of the post - operative first month , 5/5 muscle strength was achieved . an 11-year - old girl presented to the neurosurgery clinic complaining of gradual weakness of foot dorsiflexion , which was first noted 4 months prior to admission . she was evaluated for possible intervertebral disk pathology , but the radiologic studies were normal . she was referred to a physical therapy and rehabilitation clinic . by the time she consulted with our department , her ankle and toe extensors were assessed as mrc grade 2 without any sensory deficit . radiologic examination showed osteochondroma that was accompanied by a bursitis at the level of the proximal fibula , causing peroneal nerve entrapment . pathologic evaluation showed osteochondroma . by the third week following surgery , gradual increase of the muscle strength was noted . a 14-year - old boy presented to the neurosurgery clinic with weakness of foot dorsiflexion that was first noticed five months prior . upon spinal examination for rehabilitation purposes , the ankle and toe extensor was evaluated as mrc grade 2 without sensory deficit . during the electromyogram radiologic examination showed osteochondroma accompanied by a bursitis at the level of proximal fibula , causing peroneal nerve entrapment . a 10-year - old girl presented to the physical therapy and rehabilitation center and neurosurgery clinic with spinal pathologies that started three months prior due to her complaint of right drop foot . the patient was examined and dorsiflexion of the ankle and toe was determined as mrc grade 1 without any sensory deficit . radiologic examination showed osteochondroma accompanied by a bursitis at the level of the proximal fibula , causing peroneal nerve entrapment . pathologic examination results indicated osteochondroma . a week after the surgery , the muscle began to gain strength . a 2.5-year - old boy presented to the neurosurgery clinic with the complaint of limping that started shortly after beginning to walk . his neurologic background history and examination included cranial and comprehensive spinal mri for embolisms and congenital anomalies . all test results were negative for etiologic factors and the patient was referred to a physical therapy and rehabilitation clinic for six months . during the physical examination , simple gait analysis revealed missing dorsiflexion of the right foot . according to the medical research council ( mrc ) scale , further radiologic evaluation by plain x - rays , computerized tomography ( ct ) and magnetic resonance imaging ( mri ) displayed a posterolateral exostosis on the fibular neck ( fig . 1 ) . surgery was performed , and an osteochondroma , including its cartilage cap , was removed . pathologic examination revealed an osteochondroma with a thin , 2-mm cartilage cap . in the early post - operative period , electrostimulation and active and passive range of motion ( rom ) exercises were initiated . within three months following surgery , full recovery of motor functions was observed . one year after surgery , electromyogram results indicated normal excitations , and recurrence of the tumor was not noted ( table 1 ) . a 15-year - old boy presented to the physical therapy and rehabilitation center ( ptrc ) complaining of inability to dorsiflex his left toe for five months . no improvement was detected with vigorous ptrc ; therefore , the patient was referred to a neurosurgery clinic , where spinal mri studies were conducted . no improvement of the condition was observed , and the patient was referred to our department . the patient was examined , and dorsiflexion of the ankle and toe was determined as mrc grade 1 without any sensory deficit . radiologic assessment detected compression of the peroneal nerve due to an osteochondroma of the proximal fibula and fatty degeneration of the proximal musculotendiosis area of extensor hallucis longus . hourglass constriction of the peroneal truncus at the level of the fibular neck by an osteochondroma was observed . pathologic specimens depicted an osteochondroma . within the first 24  h following the surgery , electrical stimulation , accompanying active and passive range of motion exercises , was started . at the end of the post - operative first month , 5/5 muscle strength was achieved . an 11-year - old girl presented to the neurosurgery clinic complaining of gradual weakness of foot dorsiflexion , which was first noted 4 months prior to admission . she was evaluated for possible intervertebral disk pathology , but the radiologic studies were normal . she was referred to a physical therapy and rehabilitation clinic . by the time she consulted with our department , her ankle and toe extensors were assessed as mrc grade 2 without any sensory deficit . radiologic examination showed osteochondroma that was accompanied by a bursitis at the level of the proximal fibula , causing peroneal nerve entrapment . pathologic evaluation showed osteochondroma . by the third week following surgery , gradual increase of the muscle strength was noted . a 14-year - old boy presented to the neurosurgery clinic with weakness of foot dorsiflexion that was first noticed five months prior . upon spinal examination for rehabilitation purposes , the patient was referred to the physical therapy and rehabilitation clinic . upon admission , the ankle and toe extensor was evaluated as mrc grade 2 without sensory deficit . during the electromyogram radiologic examination showed osteochondroma accompanied by a bursitis at the level of proximal fibula , causing peroneal nerve entrapment . a 10-year - old girl presented to the physical therapy and rehabilitation center and neurosurgery clinic with spinal pathologies that started three months prior due to her complaint of right drop foot . the patient was examined and dorsiflexion of the ankle and toe was determined as mrc grade 1 without any sensory deficit . radiologic examination showed osteochondroma accompanied by a bursitis at the level of the proximal fibula , causing peroneal nerve entrapment . pathologic examination results indicated osteochondroma . a week after the surgery , the muscle began to gain strength . the increasing number of fascicles in this area , expansion of epineural tissue , and nerve 's unprotected surface transition play an important role in this pathology . the peroneal nerve is connected to the fibular head and is subjected to the movements of the fibula . spur or tumoral structure formation of the tubular bones can potentially apply pressure to the surrounding structures . flores and koerbel reported a case of peroneal nerve compression resulting from fibular head exostosis . only a few cases of compressions of the peroneal nerve by cartilaginous exostosis have been reported thus far . however , due to their rare occurrence , lesions such as osteochondromas may be overlooked by non - orthopedic clinics . osteochondroma is the most common benign bone tumor and can cause a variety of symptoms . depending on the location of the lesion pain , a palpable mass , puffiness  ( inflammation ) , and tinel 's sign might be significant clinical symptoms and findings . furthermore , when an exositosis accompanying stiffness is diagnosed , hereditary multiple exositosis syndrome must be considered . motor deficits are more common than sensory nerve lesions , which might be explained by the arrangement of the fascicles inside the common peroneal nerve . the exostosis grows from the bone surface to the periphery , compressing the motor fibers earlier . this is most likely due to medial placement of the motor branches within the nerve so that they are more prone to injury by a newly forming osteochondroma . advanced knowledge of the peroneal nerve anatomy as well as the mri and ct scan assessments of the lesion are key factors for preventing complications . a surgery for an osteochondroma causing peroneal nerve entrapment should be performed within three months ; otherwise , the surgical success rate decreases . although the mean time that passed until the patients consulted with us was 5.7 months ( range : 312 months ) , the loss of muscle strength in our cases fully recovered following surgery . the mean age of our patients was low , which could have played a role in the fast and complete neurological recovery ( mean age 10.5 ( 2.515 years ) ) . in spite of its frequent occurrence , drop foot associated with peroneal nerve entrapment by an osteochondroma is not easily remembered and diagnosed . especially in pediatric patients , drop foot can be overlooked during physical examination and may even be more difficult to detect in non - orthopedic clinics . with careful physical examination along with radiologic and electrophysiologic studies , nerve entrapment can be easily diagnosed , enabling surgeons to perform surgery in a timely manner , thus preventing further sequelae . written informed consent was obtained from each patient for the publication of this case report and accompanying images . a copy of the written consent is available for review by the editor - in - chief of this journal . all authors have been equally involved in the collection of data and drafting of the manuscript .
introductionthe fibular nerve is the most frequent site of neural entrapment in the lower extremity and the third most common site in the body , following the median and ulnar nerves . the peroneal nerve is commonly injured upon trauma . 
 additionally , a dropped foot might be a symptom related to the central nervous system or spinal pathologies in pediatric patients . 
 entrapment of the peripheral nerve as an etiologic cause should be kept in mind and further analyzed in orthopedic surgery clinics.presentation of casein this study , the evaluation and treatment results of five patients with no history of trauma , who underwent diagnostic procedures and treatment in various clinics ( physical therapy and rehabilitation and neurosurgery ) , are reported . 
 the patients underwent several treatments without diagnosis of the primary etiology . upon initial consultation at our department , osteochondroma at the proximal fibula was detected after physical examination and radiologic assessment . during surgery , 
 the peroneal nerve was dissected , starting from a level above the knee joint . following nerve release , 
 the osteochondroma was removed , including its cartilage cap . 
 consequently , recovery was observed in all five cases after surgery.discussionmany factors may cause non - traumatic neuropathies . 
 however , due to their rare occurrence , lesions such as osteochondromas may be overlooked at non - orthopedic clinics . 
 nerve entrapment due to proximal fibular osteochondroma is rare . 
 surgical treatment planning plays a critical role in nerve entrapment cases.conclusiondespite its frequent occurrence , a drop foot associated with peroneal nerve entrapment by an osteochondroma is not easily remembered and diagnosed . especially in pediatric cases , inadequate clinical consultation and a lack of appropriate radiologic studies may result in a delay in diagnosing peroneal nerve lesions .