The blood supply of the common peroneal nerve in the popliteal fossa

Intraneural vascularity of the median, ulnar and common peroneal nerve: Microvascular ultrasound and pathophysiological implications

Objectives

Changes in the microvascular environment are considered crucial in the pathogenesis of compression neuropathies. Several studies have demonstrated elevated intraneural vascularity in severe neuropathy compared with healthy subjects, where intraneural vascularity is considered predominantly undetectable. The aim of this study was to assess and quantify intraneural vasculature by superb microvascular imaging (SMI) in healthy volunteers in the median, ulnar and common peroneal nerve.

Methods

Intraneural vascularity was quantified in 26 healthy volunteers (312 segments overall) by SMI sonography using a 22-MHz linear transducer. Individual nerve segment vascularity was compared with the mean vascularity using one-way ANOVA and Kruskal-Wallis tests, respectively. Vendor-provided quantification and manual vessel count were compared by linear regression analysis.

Results

Intraneural vascularity was detectable in all nerve segments (100.0%). Vessel density was highest in the median nerve at the wrist (1.54 ± 0.44/mm2, P < 0.0001) and lowest in the sulcal ulnar nerve (0.90 ± 0.34/mm2, P < 0.0001). Vendor-provided automated quantification severely overestimated vascular content compared with manual quantification.

Conclusion

Superb microvascular imaging can facilitate the visualisation of nerve vascularity and even detect local variations in vessel density. The pathophysiological implications for peripheral neuropathies, especially compression neuropathies, warrant further investigation, but the absence of visible intraneural vasculature as a negative finding in the diagnostic of compression neuropathies should be interpreted with caution, as the intraneural vascularity may lie beyond the 18 MHz resolution power of a transducer.

Neuromonitoring for Proximal Fibular Osteochondroma Excision

BACKGROUND

The peroneal nerve is at risk when excising tumors in the proximal fibula. The rate of nerve injuries during proximal fibular tumor resection varies from 3% to 20%. Our goal was to report our experience with resection of osteochondromas in the proximal fibula and describe the technique and utility of neuromonitoring during excision of proximal fibular osteochondromas (PFO).

METHODS

Patients with a diagnosis of symptomatic PFO who had undergone excision at one institution from 1994 to 2018 were included. An institutional review board-approved retrospective review was performed. Intraoperative neuromonitoring was provided from 2006 on by a single group utilizing a multimodality protocol.

RESULTS

This study contains 29 patients who had excision of osteochondromas in the proximal fibula. Of these 29 consecutively monitored patients, there were 34 involved extremities. Intraoperative neuromonitoring alerts occurred in 10/29 (34.5%) procedures, which included 3 electromyography (EMG) (30%), 2 motor-evoked potential (20%), 1 somatosensory-evoked potential (10%), and 4 alerts with a combination of EMG/motor-evoked potential/somatosensory-evoked potential changes (40%). The interventions that were taken resulted in resolution of the neuromonitoring changes in all procedures. Postoperatively, we noted 2 (6.9%) new mild sensory deficits, which resolved during follow up. There were 3 patients in whom pre-existing sensory-motor deficits improved but not completely after surgery, 1 motor weakness, and 2 with residual paresthesia. In those initially presenting with paresis, there was improvement in 8 of the 8 extremities by the last follow-up visit. Pain as a symptom was resolved in all cases. There were no iatrogenic foot drop injuries. The average follow up was 32.2 months.

CONCLUSIONS

Neuromonitoring during PFO excision demonstrated a high number of alerts, all of which resolved following timely corrective action. The use of neuromonitoring may help decrease the risk of iatrogenic postoperative neurological deficits following fibular osteochondroma surgery.

LEVEL OF EVIDENCE

Level IV.

Is Foot Drop an Underreported Sequela of Extracorporeal Membrane Oxygenation?

Foot drop in the absence of limb ischemia is a chronic complication in peripheral venoarterial extracorporeal membrane oxygenation (V-A ECMO) survivors; however, there is little published regarding the incidence and functional outcomes of this condition. Common peroneal nerve is the most common cause of foot drop, a condition that leads to significant debility and requires extensive physical therapy and rehabilitation, thereby affecting the patient's quality of life. We completed a retrospective review of 153 patients who received femoral cannulation for V-A ECMO support for greater than 1 hour. The incidence of foot drop in our V-A ECMO population was 7.8% (12/153). Importantly, only two patients with foot drop were discharged home. The majority (10/12) of patients with foot drop required in-patient rehabilitation; five patients were nonambulatory, and five patients required an ankle foot orthosis assistive device. This study identifies foot drop as a relevant complication in peripherally cannulated V-A ECMO survivors and provides an initial incidence rate. By raising awareness of this complication in the V-A ECMO population, an early diagnosis is possible, which can enable appropriate rehabilitation. Prospective trials are needed to identify possible risk factors of foot drop and methods to reduce this complication of V-A ECMO.

Traumatic Peroneal Nerve Injuries: A Systematic Review

BACKGROUND

The common peroneal nerve (CPN) is the most commonly injured peripheral nerve of the lower extremity in patients with trauma. Traumatic CPN injuries have historically been associated with relatively poor outcomes and patient satisfaction, although improved surgical technique and novel procedures appear to improve outcomes. Given the variety of underlying injury modalities, treatment options, and prognostic variables, we sought to evaluate and summarize the current literature on traumatic CPN injuries and to provide recommendations from an analysis of the included studies for treatment and future research.

METHODS

A systematic review was performed using PubMed, Embase, and Cochrane databases per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Search terms consisted of variations of "peroneal nerve" or "fibular nerve" combined with "injury," "laceration," "entrapment," "repair," or "neurolysis." Information with regard to treatment modality, outcomes, and patient demographic characteristics was recorded and analyzed.

RESULTS

The initial search yielded 2,301 articles; 42 met eligibility criteria. Factors associated with better outcomes included a shorter preoperative interval, shorter graft length when an interposed graft was used, nerve continuity, and younger patient age. Gender or sex was not mentioned as a factor affecting outcomes in any study. Motor grades of ≥M3 on the British Medical Research Council (MRC) scale are typically considered successful outcomes. This was achieved in 81.4% of patients who underwent neurolysis, 78.8% of patients who underwent end-to-end suturing, 49.0% of patients who underwent nerve grafting, 62.9% of patients who underwent nerve transfer, 81.5% of patients who underwent isolated posterior tibial tendon transfer (PTTT), and 84.2% of patients who underwent a surgical procedure with concurrent PTTT.

CONCLUSIONS

Studies included in this review were heterogenous, complicating our ability to perform further analysis. It is not possible to uniformly advocate for the best treatment option, given diverse injury modalities and patient presentations and a variety of prognostic factors. Many studies do not show outcomes with respect to injury modality. Future studies should show preoperative muscle strengths and should clearly define outcomes based on the injury modality and surgical treatment option. This would allow for greater analysis of the most appropriate treatment option for a given mechanism of injury. Newer surgical techniques are promising and should be further explored.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Current Concepts Review: Common Peroneal Nerve Palsy After Knee Dislocations

Dislocation of the native knee represents a challenging injury, further complicated by the high rate of concurrent injury to the common peroneal nerve (CPN). Initial management of this injury requires a thorough neurovascular examination, given the prevalence of popliteal artery injury and limb-threatening ischemia. Further management of a knee dislocation with associated CPN palsy requires coordinated care involving the sports surgeon for ligamentous knee reconstruction and the peripheral nerve surgeon for staged or concurrent peroneal nerve decompression and/or reconstruction. Finally, the foot and ankle surgeon is often required to manage a foot drop with a distal tendon transfer to restore foot dorsiflexion. For instance, the Bridle Procedure-a modification of the anterior transfer of the posterior tibialis muscle, under the extensor retinaculum, with tri-tendon anastomosis to the anterior tibial and peroneus longus tendons at the anterior ankle-can successfully return patients to brace-free ambulation and athletic function following CPN palsy. Cross-discipline coordination and collaboration is essential to ensure appropriate timing of operative interventions and ensure maintenance of passive dorsiflexion prior to tendon transfer.

Prognostic factors in patients who underwent surgery for common peroneal nerve injury: a nest case-control study

Background

Common peroneal nerve (CPN) injury is one of the most common nerve injuries in the lower extremities and the motor functional recovery of injured common peroneal nerve (CPN) was often unsatisfactory, the mechanism of which is still controversial. The purpose of this retrospective study was to determine the prognostic factors in patients who underwent surgery for CPN injury and provide a tool for clinicians to assess the patients’ prognosis.

Methods

This is a retrospective cohort study of all patients who underwent neural exploration for injured CPN from 2009 to 2019. A total of 387 patients with postoperative follow-up more than 12 months were included in the final analysis. We used univariate logistics regression analyses to explore explanatory variables which were associated with recovery of neurological function. By applying multivariable logistic regression analysis, we determined variables incorporated into clinical prediction model, developed a nomogram by the selected variables, and then assessed discrimination of the model by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.

Results

The case group included 67 patients and the control group 320 patients. Multivariate logistic regression analysis showed that area (urban vs rural, OR = 3.35), occupation(“blue trouser” worker vs “white-trouser” worker, OR = 4.39), diabetes (OR = 11.68), cardiovascular disease (OR = 51.35), knee joint dislocation (OR = 14.91), proximal fibula fracture (OR = 3.32), tibial plateau fracture (OR = 9.21), vascular injury (OR = 5.37) and hip arthroplasty (OR = 75.96) injury increased the risk of poor motor functional recovery of injured CPN, while high preoperative muscle strength (OR = 0.18) and postoperative knee joint immobilization (OR = 0.11) decreased this risk of injured CPN. AUC of the nomogram was 0.904 and 95% CI was 0.863–0.946.

Conclusions

Area, occupation, diabetes, cardiovascular disease, knee joint dislocation, proximal fibula fracture, tibial plateau fracture, vascular injury and hip arthroplasty injury are independent risk factors of motor functional recovery of injured CPN, while high preoperative muscle strength and postoperative knee joint immobilization are protective factors of motor functional recovery of injured CPN. The prediction nomogram can provide a tool for clinicians to assess the prognosis of injured CPN.

Evaluation and Treatment of Foot Drop Using Nerve Transfer Techniques

Foot drop represents a complex pathologic condition, requiring a multidisciplinary approach for appropriate evaluation and treatment. Multiple etiologic factors require recognition before considering invasive/operative intervention. When considering surgical management for the treatment of foot drop, it is first and foremost imperative to establish the cause of the condition. Not all causes resulting in clinical foot drop have surgical options. Establishing a cause allows the provider to more appropriately curtail a multidisciplinary approach to working-up, and ultimately, treating the patient. The authors offer an algorithm for evaluating and treating foot drop conditions associated with lumbar spine radiculopathy and peripheral nerve lesions.

Tibialis posterior (TP) tendon transfer for foot drop: A single center experience

BACKGROUND

Foot drop defined as a significant weakness of ankle and toe dorsiflexion. It leads to high stepping gait, functional impairment and deformity of the foot. Objective of this study was to assess the functional outcome of tibialis posterior (TP) transfer for patient with foot drop in a single center.

METHODS

This is a retrospective study included 20 patients operated for foot drop of >1 year duration in the last 5 years. Preoperative assessment of muscles of all the three compartment of leg along with radiological assessment of ankle to rule out tarsal disintegration and ankle instability was done. Postoperatively gait, active dorsi/plantar flexion and the range of movement of the ankle and toes were assessed.

RESULTS

Tibialis posterior transfer was performed on 20 patients (16 males and 4 females, mean age 31.4 years). Commonest cause of foot drop was Hansen's disease followed by post traumatic peroneal nerve damage and post injection sciatic neuropathy. At mean follow-up of 2 years, all patients, except one, could walk with heel-toe gait without any orthotic support. There was no pain, ruptures or infections of the transferred tendons. 19 of the 20 operated ankles had mean active dorsiflexion of 7.5°, the active plantar flexion of 36.25°, and the total range of movement 43.75°. The active dorsiflexion of the toes ranged from 5-20°.

CONCLUSION

Dynamic tibialis posterior transfer gives good results in terms of normal gait, high patients' satisfaction with minimal donor site morbidity and low complication rate.

Monomelic Ischemic Neuropathy of the Tibial and Peroneal Nerve After Onyx Embolization of Vasa Nervorum Supplying a Surgically Excluded Popliteal Artery Aneurysm

Ischemic neuropathy is an exceedingly rare complication after peripheral artery embolization. We report a case of ischemic damage to the tibial and peroneal nerve after embolization of the vasa nervorum that served as feeding collaterals to a surgically excluded popliteal artery aneurysm.

Lariat sign: An MRI finding associated with common peroneal nerve rupture

Traumatic knee dislocation represents a catastrophic orthopedic injury with potentially devastating vascular and neurologic injuries. We report a case of common peroneal nerve rupture sustained during a knee dislocation with novel radiographic findings that we describe as a lariat sign. At the site of rupture, the distal nerve loops back on itself forming a lasso shape or lariat. This thickened nerve's abnormal course should not be misinterpreted as a vessel.

Causes of peroneal neuropathy associated with orthopaedic leg lengthening in different canine models

Peroneal neuropathy is one of the complications of orthopaedic leg lengthening. Methods of treatment include slowing of distraction and decompression both of which may lead to additional complications. The purpose of this study was to analyse the changes in histologic peroneal nerve structure during experimental orthopaedic lengthening using various modes of manual or automatic distraction. The obtained data provide the basis for better understanding of peroneal neuropathy pathogenesis and refinement of prophylaxis and preventive treatment protocols. Four experimental models of canine leg lengthening using the Ilizarov fixator were studied: 1 (n = 10)—manual distraction—1 mm/day divided into four increments; 2 (n = 12)—automatic distraction—1 mm/day in 60 increments, 3 (n = 9) and 4 (n = 9)—increased rate of high frequency automatic distraction: 3 mm/day in 120 and 180 increments, respectively. In peroneal nerves semi-thin sections cross-sectional fascicular areas, content of adipocytes in epineurium, endoneurial vascularisation, morphometric parameters of nerve fibres were assessed by computerised analysis at the end of distraction and of consolidation periods and 30 days after fixator removal. In Groups 1–2 massive nerve fibre degeneration along with epineural vessels obliteration was revealed in two cases from 22, whereas in Groups 3–4 there were 10 from 18 (p < 0.01). Injuries of perineurium and endoneurial vessels were noted in Group 3, and long-lasting thinning of nerve fascicles in Group 4. The decrease in epineurial fat tissue was revealed in all groups, more drastic in 3. Modifications and injuries of nerve sheaths and blood vessels depending on distraction rate and frequency contribute to peroneal neuropathy. Its mechanical, circulatory and metabolic causes are discussed.

Common Peroneal Neuropathy With Anterior Tibial Artery Occlusion: A Case Report

Peroneal neuropathy is a common mononeuropathy of the lower limb. Some studies have reported cases of peroneal neuropathy after vascular surgery or intervention. However, no cases of peroneal neuropathy with occlusion of a single peripheral artery have been previously reported. A 73-year-old man was referred with a 3-week history of left-sided foot drop. He had a history of valvular heart disease and arrhythmia, and had previously been treated with percutaneous coronary intervention. Computed tomography angiogram of the lower extremity showed proximal occlusion of the left anterior tibial artery. An electrodiagnostic study confirmed left common peroneal neuropathy. After diagnosis, anticoagulation therapy was started and he received physical therapy.

Traumatic Knee Dislocations: Evaluation, Management, and Surgical Treatment

Knee dislocations are catastrophic injuries that demand emergent evaluation and often require a multidisciplinary approach. Long-term outcome studies are relatively scarce secondary to the variability in any given study population and the wide variety of injury patterns between knee dislocations. Multiple controversies exist with regard to outcomes using various treatment methods (early vs late intervention, graft selection, repair vs reconstruction of medial and lateral structures, rehabilitation regimens). Careful clinical evaluation is essential when knee dislocation is suspected.

Endogenous opioid activity in the anterior cingulate cortex is required for relief of pain

Pain is aversive, and its relief elicits reward mediated by dopaminergic signaling in the nucleus accumbens (NAc), a part of the mesolimbic reward motivation pathway. How the reward pathway is engaged by pain-relieving treatments is not known. Endogenous opioid signaling in the anterior cingulate cortex (ACC), an area encoding pain aversiveness, contributes to pain modulation. We examined whether endogenous ACC opioid neurotransmission is required for relief of pain and subsequent downstream activation of NAc dopamine signaling. Conditioned place preference (CPP) and in vivo microdialysis were used to assess negative reinforcement and NAc dopaminergic transmission. In rats with postsurgical or neuropathic pain, blockade of opioid signaling in the rostral ACC (rACC) inhibited CPP and NAc dopamine release resulting from non-opioid pain-relieving treatments, including peripheral nerve block or spinal clonidine, an α2-adrenergic agonist. Conversely, pharmacological activation of rACC opioid receptors of injured, but not pain-free, animals was sufficient to stimulate dopamine release in the NAc and produce CPP. In neuropathic, but not sham-operated, rats, systemic doses of morphine that did not affect withdrawal thresholds elicited CPP and NAc dopamine release, effects that were prevented by blockade of ACC opioid receptors. The data provide a neural explanation for the preferential effects of opioids on pain affect and demonstrate that engagement of NAc dopaminergic transmission by non-opioid pain-relieving treatments depends on upstream ACC opioid circuits. Endogenous opioid signaling in the ACC appears to be both necessary and sufficient for relief of pain aversiveness.

Is peroneal nerve injury associated with worse function after knee dislocation?

BACKGROUND

Peroneal nerve palsy is a frequent and potentially disabling complication of multiligament knee dislocation, but little information exists on the degree to which patients recover motor or sensory function after this injury, and whether having this nerve injury--with or without complete recovery--is a predictor of inferior patient-reported outcome scores.

QUESTIONS/PURPOSES

The purposes of this study were to (1) report on motor and sensory recovery as well as patient-reported outcomes scores of patients with peroneal nerve injury from multiligament knee dislocation; (2) compare those endpoints between patients who had partial versus complete nerve injuries; and (3) compare patient-reported outcomes among patients who sustained peroneal nerve injuries after knee dislocation with a matched cohort of multiligament knee injuries without nerve injury.

METHODS

Thirty-two patients were identified, but five did not have 2-year followup and are excluded (16% lost to followup). Twenty-seven patients (24 male, three female) with peroneal nerve injury underwent multiligament knee reconstruction and were followed for 6.3 years (range, 2-18 years). Motor grades were assessed by examination and outcomes by International Knee Documentation Committee (IKDC) and Lysholm scores. Retrospectively, patients were divided into complete (n = 9) and partial nerve palsy (n = 18). Treatment for complete nerve palsy included an ankle-foot orthosis for all patients, nonoperative (one), neurolysis (two), tendon transfer (three), nerve transfer (one), and combined nerve/tendon transfer (one). Treatment for partial nerve palsy included nonoperative (12), neurolysis (four), nerve transfer (one), and combined nerve/tendon transfer (one). Furthermore, patients without nerve injury were matched by Schenck classification, age, and sex. Data were analyzed using univariate and multivariate models.

RESULTS

Overall, 18 patients (69%) regained antigravity ankle dorsiflexion after treatment (three complete nerve palsy [38%] versus 15 partial nerve palsy [83%]; p = 0.06). One patient with complete nerve palsy (13%) and 13 patients with partial nerve palsy (72%) regained antigravity extensor hallucis longus strength (p = 0.01). IKDC and Lysholm scores were similar between complete nerve palsy and partial nerve palsy groups. After controlling for confounding variables such as patient age, body mass index, injury interval to surgery, mechanism of injury, bicruciate injury, and popliteal artery injury status, there was no difference between patients with peroneal nerve injury and those without on Lysholm or IKDC scores.

CONCLUSIONS

With multiligament knee dislocation and associated peroneal nerve injury, patients with partial nerve injury are more likely to regain antigravity strength when compared with those with a complete nerve injury, but their overall function may not improve. After controlling for confounding variables in a multivariate model, there was no difference in Lysholm or IKDC scores between patients with peroneal nerve injury and those without.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Treatment of peroneal nerve injuries with simultaneous tendon transfer and nerve exploration

Background

Common peroneal nerve palsy leading to foot drop is difficult to manage and has historically been treated with extended bracing with expectant waiting for return of nerve function. Peroneal nerve exploration has traditionally been avoided except in cases of known traumatic or iatrogenic injury, with tendon transfers being performed in a delayed fashion after exhausting conservative treatment. We present a new strategy for management of foot drop with nerve exploration and concomitant tendon transfer.

Method

We retrospectively reviewed a series of 12 patients with peroneal nerve palsies that were treated with tendon transfer from 2005 to 2011. Of these patients, seven were treated with simultaneous peroneal nerve exploration and repair at the time of tendon transfer.

Results

Patients with both nerve repair and tendon transfer had superior functional results with active dorsiflexion in all patients, compared to dorsiflexion in 40% of patients treated with tendon transfers alone. Additionally, 57% of patients treated with nerve repair and tendon transfer were able to achieve enough function to return to running, compared to 20% in patients with tendon transfer alone. No patient had full return of native motor function resulting in excessive dorsiflexion strength.

Conclusion

The results of our limited case series for this rare condition indicate that simultaneous nerve repair and tendon transfer showed no detrimental results and may provide improved function over tendon transfer alone.

Vasculitic neuropathy

Vasculitis is a primary phenomenon in autoimmune diseases such as polyarteritis nodosa, Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, and essential mixed cryoglobulinemia. As a secondary feature vasculitis may complicate, for example, connective tissue diseases, infections, malignancies, and diabetes. Vasculitic neuropathy is a consequence of destruction of the vessel wall and occlusion of the vessel lumen of small epineurial arteries. Sometimes patients present with nonsystemic vasculitic neuropathy, i.e., vasculitis limited to peripheral nerves and muscles with no evidence of further systemic involvement. Treatment with corticosteroids, sometimes in combination with other immunosuppressants, is required to control the inflammatory process and prevent further ischemic nerve damage.

Similarities and dissimilarities of the blood supplies of the human sciatic, tibial, and common peroneal nerves

The aim was to investigate the arterial supply of the sciatic, tibial, and common peroneal nerves. Thirty-six lower limbs of 18 human fetuses were studied. The fetuses had been fixed in buffered formalin and the blood vessels injected with barium sulfate. Fetal age ranged from 12 to 28 weeks of gestation. Microdissection of the fetal lower extremities was done under ×5 magnifying lenses. The sciatic nerves of 10 lower extremities were dissected and excised and radiographs taken. The extraneural arterial chain of the sciatic nerve was composed of 2-6 arterial branches of the inferior gluteal artery, the medial circumflex femoral artery, the perforating arteries, and the popliteal artery. The extraneural arterial chain of tibial nerve was composed of 2-5 arteries, which were branches of the popliteal, the peroneal, and the posterior tibial arteries. Radiographs showed the presence of complete intraneural arterial chains in the sciatic and tibial nerves, formed from anastomosing vessels. Dissection showed that, in 97.2% of the specimens, the common peroneal nerve was supplied only by one popliteal artery branch, the presence of which was confirmed radiologically. The sciatic and tibial nerves are supplied by numerous arterial branches of different origins, which provide for collateral circulation. In contrast, the common peroneal nerve is most frequently supplied only by one elongated longitudinal blood vessel, a branch of the popliteal artery. Such a vascular arrangement may make the common peroneal nerve less resistant to stretching and compression.

Risk factors for peroneal nerve injury and recovery in knee dislocation

BACKGROUND

Acute knee dislocation is rare but has a high rate of associated neurovascular injuries and potentially limb-threatening complications. These include the substantial morbidity associated with peroneal nerve injury: neuropathic pain, decreased mobility, and considerably reduced function, which not only impairs patient function but complicates treatment.

QUESTIONS/PURPOSES

We therefore identified and quantified the risks associated with specific factors for peroneal nerve injury and recovery in patients with knee dislocations.

PATIENTS AND METHODS

We retrospectively reviewed the charts of 26 patients, from among a cohort of all 91 knee dislocations, with a peroneal nerve palsy over a 5-year period. We then used univariable and multivariable statistics to identify risk factors predicting peroneal nerve injury and recovery.

RESULTS

Gender (odds ratio, 5.47), body mass index (odds ratio, 1.14), and fibular head fracture (odds ratio, 4.77) were associated with peroneal nerve injury. Only younger age was associated with peroneal nerve recovery.

CONCLUSIONS

Knowledge of the risk factors for peroneal nerve injury and the predictors of recovery in knee dislocation allows the treating surgeon to have a better understanding of the nature of the neurologic injury and modify management based on the anticipated return of nerve function.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Transient inflammation-induced ongoing pain is driven by TRPV1 sensitive afferents

Background

Neuropathic pain is a chronic disease resulting from dysfunction within the "pain matrix". The basolateral amygdala (BLA) can modulate cortical functions and interactions between this structure and the medial prefrontal cortex (mPFC) are important for integrating emotionally salient information. In this study, we have investigated the involvement of the transient receptor potential vanilloid type 1 (TRPV1) and the catabolic enzyme fatty acid amide hydrolase (FAAH) in the morphofunctional changes occurring in the pre-limbic/infra-limbic (PL/IL) cortex in neuropathic rats.

Results

The effect of N-arachidonoyl-serotonin (AA-5-HT), a hybrid FAAH inhibitor and TPRV1 channel antagonist, was tested on nociceptive behaviour associated with neuropathic pain as well as on some phenotypic changes occurring on PL/IL cortex pyramidal neurons. Those neurons were identified as belonging to the BLA-mPFC pathway by electrical stimulation of the BLA followed by hind-paw pressoceptive stimulus application. Changes in their spontaneous and evoked activity were studied in sham or spared nerve injury (SNI) rats before or after repeated treatment with AA-5-HT. Consistently with the SNI-induced changes in PL/IL cortex neurons which underwent profound phenotypic reorganization, suggesting a profound imbalance between excitatory and inhibitory responses in the mPFC neurons, we found an increase in extracellular glutamate levels, as well as the up-regulation of FAAH and TRPV1 in the PL/IL cortex of SNI rats. Daily treatment with AA-5-HT restored cortical neuronal activity, normalizing the electrophysiological changes associated with the peripheral injury of the sciatic nerve. Finally, a single acute intra-PL/IL cortex microinjection of AA-5-HT transiently decreased allodynia more effectively than URB597 or I-RTX, a selective FAAH inhibitor or a TRPV1 blocker, respectively.

Conclusion

These data suggest a possible involvement of endovanilloids in the cortical plastic changes associated with peripheral nerve injury and indicate that therapies able to normalize endovanilloid transmission may prove useful in ameliorating the symptoms and central sequelae associated with neuropathic pain.

Transient inflammation-induced ongoing pain is driven by TRPV1 sensitive afferents

BACKGROUND

Tissue injury elicits both hypersensitivity to evoked stimuli and ongoing, stimulus-independent pain. We previously demonstrated that pain relief elicits reward in nerve-injured rats. This approach was used to evaluate the temporal and mechanistic features of inflammation-induced ongoing pain.

RESULTS

Intraplantar Complete Freund's Adjuvant (CFA) produced thermal hyperalgesia and guarding behavior that was reliably observed within 24 hrs and maintained, albeit diminished, 4 days post-administration. Spinal clonidine produced robust conditioned place preference (CPP) in CFA treated rats 1 day, but not 4 days following CFA administration. However, spinal clonidine blocked CFA-induced thermal hyperalgesia at both post-CFA days 1 and 4, indicating different time-courses of ongoing and evoked pain. Peripheral nerve block by lidocaine administration into the popliteal fossa 1 day following intraplantar CFA produced a robust preference for the lidocaine paired chamber, indicating that injury-induced ongoing pain is driven by afferent fibers innervating the site of injury. Pretreatment with resiniferatoxin (RTX), an ultrapotent capsaicin analogue known to produce long-lasting desensitization of TRPV1 positive afferents, fully blocked CFA-induced thermal hypersensitivity and abolished the CPP elicited by administration of popliteal fossa lidocaine 24 hrs post-CFA. In addition, RTX pretreatment blocked guarding behavior observed 1 day following intraplantar CFA. In contrast, administration of the selective TRPV1 receptor antagonist, AMG9810, at a dose that reversed CFA-induced thermal hyperalgesia failed to reduce CFA-induced ongoing pain or guarding behavior.

CONCLUSIONS

These data demonstrate that inflammation induces both ongoing pain and evoked hypersensitivity that can be differentiated on the basis of time course. Ongoing pain (a) is transient, (b) driven by peripheral input resulting from the injury, (c) dependent on TRPV1 positive fibers and (d) not blocked by TRPV1 receptor antagonism. Mechanisms underlying excitation of these afferent fibers in the early post-injury period will offer insights for development of novel pain relieving strategies in the early post-traumatic period.

Diagnosis and management of knee dislocations

An acute knee dislocation is an uncommon injury, with a high rate of associated vascular and neurologic injuries as well as potentially limb-threatening complications. High-energy trauma is the most common cause of an acute knee dislocation, although lower-energy injuries, such as those sustained during athletic competition, are increasing in incidence. Injuries to the popliteal artery and common peroneal nerve are relatively common, requiring a high index of suspicion and complete neurovascular examination in a timely fashion. All cases of suspected knee dislocation should have an ankle-brachial index performed, reserving arteriography for those with an abnormal finding. Initial management consists of closed reduction, if possible, and application of a hinged brace or external fixator. Definitive management remains an area of controversy, although anatomic surgical repair or reconstruction is favored by most surgeons to help optimize knee function. Most patients treated for a knee dislocation can expect to return to their daily activities, but with less predictable returns to sporting activities.

Extraneural arterial blood vessels of human fetal sciatic nerve

Nerves get segmental blood supply either from the neighboring muscular and cutaneous branches or from the regional main arterial trunks. The aim of our research was to detect, in the gluteal and posterior femoral region, the blood vessels which are involved in the blood supply of the human fetal sciatic nerve, as well as to establish their origin. Micro-dissection was performed on 48 fetal lower extremities which were previously fixed in 10% formalin. Micropaque solution (barium sulfate) was injected into their blood vessels. The fetal gestational age was established by measuring the crump-crown length and it ranged from the third to the ninth lunar month. The observed nutritional arteries of the human sciatic nerve originated from the inferior gluteal artery, medial circumflex femoral artery, perforating branches, and popliteal artery. The anastomotic arterial chain of the human sciatic nerve was observed in all cases. In 75% of the cases it was composed of the branches of the inferior gluteal artery, the medial circumflex femoral artery and the first two perforating arteries. The nutrient branch of the third perforating branch was less frequently (in 14.5% of the cases) part of this anastomotic arterial chain.

Difference in Recovery Potential of Peripheral Nerves after Graft Repairs

OBJECTIVE:

To our knowledge, few studies have been published regarding differences in nerve recovery potentials. In this study, sensory and motor recovery potentials were compared between different nerves.

METHODS:

A prospective study of a homogenous group of 393 graft repairs of the median, ulnar, radial, tibial, peroneal, femoral, and musculocutaneous nerves, with the scoring of motor and sensory recoveries. Sensory and motor recovery potentials, defined on the basis of average scores and rates of useful recovery, were compared between the different nerves, and separately for high-, intermediate-, and low-level repairs.

RESULTS:

Sensory recovery potential was similar for all nerves tested (P &gt; 0.05), but motor recovery potential differed significantly. After high-level repairs, motor recovery potential was significantly better for the radial and tibial nerves (useful recovery in 66.7 and 54.5% of patients, respectively), than for the ulnar and peroneal nerves (useful recovery in 15.4 and 13.8% of patients, respectively; P &lt; 0.05). After intermediate-level repairs, motor recovery potential was better for the musculocutaneous, radial, and femoral nerves (useful recovery in 100, 98.3, and 87.5% of repairs, respectively), than for the tibial, median and ulnar nerves (useful recovery in 63.9, 52, and 43.6% of repairs, respectively; P &lt; 0.05). In addition, motor recovery potential was significantly the worst with peroneal nerve repairs (useful recovery in 15.2% of patients; P &lt; 0.05). After low-level repairs, motor recovery potential was similar for all nerves (useful recovery in the range of 88.9–100% of patients and in 56.3% of peroneal nerve repairs).

CONCLUSION:

Sensory recovery potential is similar for the median, ulnar, and tibial nerves. The expression of motor recovery potential depends on the repair level. With low- and high-level repairs, it does not stand out in an obvious way, but it is fully expressed with intermediate-level repairs, classifying nerves into three categories with excellent, moderate, and poor recovery potential.

Peripheral nerve palsies associated with closed fractures and dislocations

We have studied 178 consecutive cases of 203 patients admitted to this unit between 1999 and 2003 with diagnosis of peripheral nerve palsies associated with closed fractures and dislocations in the upper and lower limbs. Fifty-one nerves were explored, 25 of which were found partly or completely transected. Indications for surgery were high-energy transfer injury, severe neuropathic pain, failure to progress and a static Tinel's sign. Spontaneous recovery was good in only 25 of the 51 non-operated cases of high-energy transfer injury to the circumflex, radial and common peroneal nerves. Good spontaneous recovery is closely related to low-energy transfer injury, and is associated with an advancing Tinel's sign. Absence of the Tinel's sign indicates conduction block; neurophysiological investigation confirms it. We stress the particular value of the Tinel's sign, and note that severe neuropathic pain indicates continuing damage to the nerve and gives a strong reason for operation.

An anatomic study of the cephalic vein in the deltopectoral shoulder approach

There has been debate regarding medial or lateral retraction of the cephalic vein in the deltopectoral approach to the shoulder. Those who recommend lateral retraction of the vein cite multiple feeder vessels from the deltoid muscle; however, there is little evidence to support this in the orthopaedic literature. The purpose of our study was to determine if there are more lateral branches than medial branches to the cephalic vein in the deltopectoral groove. Forty fresh frozen cadaveric shoulders underwent retrograde latex injection of the cephalic vein. A deltopectoral incision was used, and the numbers of medial and lateral branches were recorded. In the deltopectoral groove there were more lateral than medial feeder vessels to the cephalic vein. There also were more branches to the vein in the proximal (1/2) of the incision compared with the distal (1/2). Most of the specimens dissected had more lateral branches to the cephalic vein than medial branches. Based on the number of feeder vessels to the cephalic vein, results of our study support lateral retraction of the cephalic vein in a majority of shoulders during the deltopectoral approach to the shoulder.