Normative values and factors affecting saphenous nerve responses in a south Asian population: a cross-sectional neurophysiological study at a tertiary care hospital in Pakistan.

BACKGROUND: The saphenous nerve, a sensory branch of the femoral nerve, is not commonly included in routine lower extremity nerve conduction studies due to a high frequency of non-recordable responses in healthy subjects. However, saphenous nerve conduction studies are sometimes utilized for the diagnostic assessment of isolated lumbosacral plexus, femoral, or saphenous mononeuropathies. Our study aims to determine normative saphenous nerve response values in a healthy Pakistani population and to investigate their associations with patient body mass index, age, and gender. METHODS: This cross-sectional descriptive study was undertaken over a 3­month period (May to July 2021) at a neurophysiology department of a tertiary care center in Pakistan. Healthy subjects underwent neurological examination, anthropometric measurements, and bilateral SN nerve conduction studies, with recording of peak-latency, peak-to-peak amplitude and conduction velocity. Statistical analyses and linear regression were conducted to evaluate associations between nerve conduction study variables and patient characteristics. Statistical analyses were also run to assess patient characteristics affecting recordability of saphenous nerve responses. A p-value < 0.05 was considered statistically significant. RESULTS: Among 117 subjects, 79.5% (n = 93) had recordable saphenous nerve responses. Median peak-latency, amplitude, and conduction velocity were 3.2 (3.0-3.3) m/s, 7.7 (5.8-9.9) uV, and 44.0 (42.0-47.0) m/s, respectively. Bilaterally absent responses were observed in 20.5% (n = 24) of subjects. Obese participants had a significantly higher number of absent saphenous responses (p = 0.033). Females had shorter peak-latency (p = 0.006) and higher conduction velocity (p = 0.012). CONCLUSIONS: Saphenous nerve responses can be used to assess unilateral femoral and saphenous nerve pathologies, provided they are recordable on the asymptomatic side for comparison. Absent bilateral saphenous nerve responses should be interpreted with caution given their prevalence in healthy individuals. Patient characteristics should be taken into consideration when interpreting recordable and nonrecordable saphenous nerve responses.

Advanced 3D Anatomical Mapping of Saphenous and Inferior Medial Genicular Nerve Branching: Enhancing Precision in Knee Joint Denervation.

BACKGROUND: Radiofrequency ablation is a common non-opioid treatment to manage chronic knee pain. The inferior medial genicular nerve is conventionally targeted. It has been suggested that the infrapatellar branch(saphenous nerve) should also be targeted. There is controversy regarding the contribution of the infrapatellar branch to the innervation of the knee joint capsule. OBJECTIVE: 1) Identify the frequency of the branching pattern(s) of the infrapatellar branch in 3D; 2) Assess spatial relationships of branches of infrapatellar branch to the inferior medial genicular nerve; 3) Determine if capturing infrapatellar branch could result in additional benefit to the existing protocol. DESIGN: Anatomical Study. METHODS: The infrapatellar branch and inferior medial genicular nerve were serially dissected, digitized, and modelled in 3D in 7 specimens(mean age 57.8 ± 2.0; 2F/5M) and their relationship documented. The spatial relationship of the nerves was used to assess the anatomical efficacy of including the infrapatellar branch in the protocol. RESULTS: The infrapatellar branch is most frequently a cutaneous nerve. This nerve was variable and found to be unbranched or have 2-3 branches and in all specimens was located superficial to the branches of inferior medial genicular nerve. When the infrapatellar branch (1) coursed more distally, the strip lesion would not capture the infrapatellar branch but would capture inferior medial genicular nerve consistently;(2) overlapped with the inferior medial genicular nerve, the strip lesion would capture both nerves. CONCLUSIONS: Proposed protocol targeting the infrapatellar branch is likely to capture the inferior medial genicular consistently regardless of the anatomical variation of the infrapatellar branch.

Infrapatellar Branch of the Saphenous Nerve: Therapeutic Approaches to Chronic Knee Pain.

PURPOSE OF REVIEW: The infrapatellar branch of the saphenous nerve (IPS) is an under-investigated nerve that can be a source of chronic knee pain. This literature review aims to deliver an up-to-date review of chronic pain transmitted via the IPS along with therapeutic approaches available for pain refractory to conservative measures. RECENT FINDINGS: Knee pain transmitted via the IPS can arise from several etiologies. Damage to the IPS is often iatrogenic and develops following total knee arthroplasty, anterior cruciate ligament reconstruction, and other knee surgical procedures. Other causes of IPS-derived pain include entrapment of the nerve, neuromas, Schwannomas, and pain from knee osteoarthritis transmitted through the IPS.This article investigated therapeutic approaches to pain derived from the IPS. Common approaches included radiofrequency ablation, neuroma excisions, Schwannoma excision, nerve blocks, surgical exploration, surgical release of an entrapped nerve, cryoablation, and peripheral nerve stimulation. Pain scores, duration of pain relief, adverse events, and secondary outcomes were all included in this review. A subset of the patient population experiences chronic pain deriving from the IPS that is refractory to conservative treatment measures. This review aims to evaluate the etiologies and therapeutic approaches for chronic pain arising from the IPS refractory to conservative treatments.

Anatomy and pathology of adductor canal (Hunter's canal).

Adductor canal (Hunter's canal) pathologies are often underdiagnosed, with the saphenous nerve being the most commonly affected. While uncommon, involvement of the femoral artery and vein can cause severe and irreversible complications if not detected early. Significant attention must be given to adductor canal pathologies because the musculoaponeurotic tunnel is predominantly fibrotic with minimal adipose tissue. As a result, any edema or space-occupying lesion can lead to early compression of the structures within the adductor canal. Incorporating adductor canal syndrome into the imaging differential diagnosis is essential. For diagnosing and sometimes managing these conditions. In this article, we describe the anatomy and spectrum of pathologies involving the Hunter's canal.

A Network Meta-Analysis of Randomized Controlled Trials Assessing Intraoperative Anesthetic Therapies for Analgesic Efficacy and Morphine Consumption Following Total Knee Arthroplasty.

BACKGROUND: The purpose of this study was to compare intraoperative anesthetic therapies for total knee arthroplasty (TKA) regarding postoperative analgesic efficacy and morphine consumption by conducting a systematic literature search. METHODS: Randomized controlled trials of TKA using various anesthetic therapies were identified from various databases from conception through December 31, 2021. A network meta-analysis of relevant literature was performed to investigate which treatment showed better outcomes. In total, 40 trials were included in this study. RESULTS: Surface under the cumulative ranking curve showed local infiltration anesthesia (LIA) with saphenous nerve block (SNB) to produce the best pain relief on postoperative days (PODs) 1 and 2 and the best reduction of morphine consumption on PODs 1 and 3. However, femoral nerve block showed the largest effect on pain relief on POD 3, and liposomal bupivacaine showed the largest effect on reduction of morphine consumption on POD 2. CONCLUSIONS: According to this network meta-analysis, surface under the cumulative ranking curve percentage showed that LIA with SNB provided the best analgesic effect after TKA. Furthermore, patients receiving LIA with SNB had the lowest consumption of morphine. Although femoral nerve block resulted in better pain relief on POD 3, LIA with SNB could be selected first when trying to reduce morphine consumption or increase early ambulation.

The objective measurement of hypoaesthesia after Total Knee Arthroplasty and its correlation with skin incision length: a prospective study.

PURPOSE: This study aims to measure the peri-incisional numbness developing after Total Knee Arthroplasty (TKA) performed using the midline skin incision. It studies the natural course of the numbness and determines its correlation with the skin incision length (SIL). MATERIALS & METHODS: 66 knees undergoing primary TKA with a standard midline incision were evaluated. The SIL and the area of numbness (AON) were measured in complete knee extension and 90° of flexion. The area was marked by the patient using a sketch pen and then determined by an independent observer using monofilament testing. The "ImageJ" software was used to calculate the area. RESULTS: All patients developed numbness around the knee after TKA. There was a statistically significant correlation between the SIL and AON in both flexion and extension at two weeks (p < 0.001) and three months (p < 0.001). However, there was a weak and insignificant correlation at six months (p = 0.217). CONCLUSION: When TKA is performed using the midline skin incision, the SIL positively correlates with the AON postoperatively during the initial short-term follow-up. At six monthly follow-ups, there is no significant correlation between the two.

Cryoneurolysis of the saphenous nerve in the pig: A proof-of-principle investigation.

OBJECTIVE: To determine if in vivo cryoneurolysis inhibits ex vivo compound action potential (CAP) conduction in the porcine saphenous nerve and if this occurs rapidly enough to justify performing the technique before stifle surgery. STUDY DESIGN: Blinded, controlled, randomized, preclinical study. ANIMALS: A group of eight healthy, 8 weeks old, intact, female pigs anesthetized for an unrelated terminal study. METHODS: Both saphenous nerves of each pig were exposed surgically, and 15 mm of a 20 gauge, closed-tip, commercial cryoneurolysis cannula were inserted cranial to each nerve within the neurovascular fascial sheath along its long axis. The cannula was only actuated on one limb, according to random allocation. Nerves were excised within 15 minutes of actuation and underwent testing in a nerve conduction chamber, where stimulus voltage was increased sequentially (from 0.1 to ≤ 1.9 V). An anesthesiologist blinded to treatment viewed recordings of time versus voltage for each nerve and answered 'yes' or 'no' when asked if an evoked CAP was observed. Fisher's exact test evaluated the incidence of CAP conduction between groups (p < 0.05 considered significant). Nerves were submitted for hematoxylin and eosin staining for blinded histopathological examination. RESULTS: A CAP was conducted in 8/8 and 1/8 of the control and treated nerves, respectively (p = 0.001). Maximal responses in control nerves were 1.92 ± 0.19 mV (mean ± standard error). In the single treated nerve that conducted a CAP, the maximal CAP amplitude was 0.4 mV, lower than the lowest maximal CAP (1.19 mV) in the control nerves. All control nerves were histologically normal, and all treated nerves displayed mild perivascular and perineural inflammation (cuffs of lymphocytes, plasma cells and eosinophils, and edema). CONCLUSIONS AND CLINICAL RELEVANCE: The rapid inhibition of CAP conduction warrants clinical investigation of saphenous cryoneurolysis for both intraoperative antinociception and postoperative analgesia in pigs undergoing experimental stifle surgery.

Unusual branch of the saphenous nerve to the sartorius muscle in a female cadaver.

PURPOSE: The saphenous nerve is a predominantly sensory nerve. It is the longest nerve of the body which supplies the skin of the medial side of the leg and foot as far as the ball of the great toe. We present here an unusual motor branch of the saphenous nerve to the sartorius muscle. METHOD: Institutional guidelines for use of human cadaver were followed. Routine dissection of the lower limbs for undergraduate medical teaching was performed in a 67 years old female cadaver employing standard methods. Relevant gross features of the variations were photographed. H&E staining of relevant structure was done and photomicrographed. RESULTS: The unusual motor branch to Sartorius was observed in the right thigh. The branch was given off in the lower third of the thigh after the saphenous nerve exited the adductor canal. The branch was distinctly seen entering the substance of the sartorius. The structure was confirmed to be a peripheral nerve by histological examination. The saphenous nerve then descended between the sartorius and gracilis tendons, pierced the fascia lata and became cutaneous. CONCLUSION: The motor branch to the sartorius muscle is a very rare branch whose knowledge is important for clinicians as it can get damaged during arthroscopy and other knee surgery or during adductor canal block.

Comparative evaluation of functional outcome and pain relief after pulsed radiofrequency of the saphenous nerve within and distal to the adductor canal in medial compartment knee osteoarthritis: A randomized double-blind trial.

Background and Aims: Pulsed radiofrequency (PRF) of the saphenous nerve (SN) has shown effective pain relief in knee pain because of knee osteoarthritis (KOA). The adductor canal (AC) contains other sensory nerves innervating the medial part of the knee joint apart from SN. We compared the PRF of SN within and outside the AC for their quality and duration of pain relief in knee osteoarthritis of the medial compartment (KOA-MC). Material and Methods: We conducted a randomized prospective study in 60 patients with anteromedial knee pain because of KOA-MC. Patients in group A received PRF-SN, and those in group B received PRF-AC. The primary objectives were comparison of pain by Visual Analog Scale (VAS) scores and changes in quality of daily living by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and OXFORD knee scores. The secondary objectives were comparison of analgesic requirements using Medicine Quantification Scale (MQS) scores and block-related complications. Intra-group comparison was performed by analysis of variance. Inter-group normally distributed data were assessed by Student's t-test, non-normally distributed and ordinal data were assessed by Mann-Whitney U-test, and categorical data were assessed by Chi-square test. A P value of <0.05 was considered significant. Results: VAS scores were significantly lower in Gr-B at 12 weeks. The WOMAC scores and OXFORD scores at 4, 8, 12, and 24 weeks were significantly lower in Gr-B compared to Gr-A. Conclusion: The PRF-AC provides better pain relief and functional outcome than PRF-SN; however, duration of pain relief was not significantly different.

Optimization of surgical exposure for harvesting gracilis-semitendinosus tendons.

PURPOSE: This study was conducted to provide anatomical data and surface markers for the safe and efficient exposure of surgical incisions for harvesting gracilis tendons (GT) and semitendinosus tendons (STT) while avoiding technical pitfalls and nerve injury during harvest for ligament reconstruction. METHODS: Seventy-four Chinese cadaveric lower limbs were dissected to expose the infrapatellar branch of the saphenous nerve (IPBSN) and pes anserinus (PA). Measurements of the borders and accessory bands of the PA tendons were taken. The arrangement of PA tendons and distribution of the IPBSN were assessed. RESULTS: The PA was roughly shaped like a quadrangle, with its superior border at the horizontal plane of the tibial tuberosity (TT). The GT and STT bifurcation point was located on the medial border of the PA. From medial side to lateral side, the sartorius tendons (ST), GT, and STT fused gradually and formed the lateral border of the PA at the distal end. The tendon arrangement of the PA was primarily affected by ST, which commonly covered GT and STT completely. Variant tendons were found in 41.9% of specimens. The insertion of the accessory bands was distal but close to the inferior border of the PA. Accessory bands were observed only in STT and ST, and STT accounted for the most. The width of the first accessory band of STT was similar to the width of the STT. Additionally, most of the IPBSNs were proximal to the horizontal plane of the TT. CONCLUSION: For clearly exposing the GT and STT, it is crucial to expose the GT and STT bifurcation point on the medial border of the PA, whether directly or indirectly through the incision.The influence of ST insertion and the variability of tendons within the PA must be paid attention to during the operation. To protect IPBSNs highly, the incision should not be higher than the TT level.

Connection between medial dorsal cutaneous nerve and saphenous nerve: case report.

PURPOSE: There are no data on the connection of the saphenous nerve (SN), located on the medial side of the foot, with the terminal branches of the superficial fibular nerve. The aim of this study is to reveal the variation that surgeons should pay attention to for anesthesia applied in foot surgeries. METHODS: In this study, the left foot of a 70-year-old female cadaver fixed with formalin was dissected. The distance to the medial malleolus and the incision line was recorded using digital caliper to determine the reference points in the resulting variation. RESULTS: It was observed that a branch from the SN, which arose from the SN and proceeded anteriorly to the upper part of the medial malleolus and continued towards the dorsum of the foot, hooked with a branch from the medial dorsal cutaneous nerve (MDCN). The branches arising from this hook were distributed on the medial edge of the foot up to the proximal metatarsophalangeal joint I. The distance of this nerve connection to the medial malleolus is 91.14 mm, and the distance to the incision line is 15.76 mm. CONCLUSIONS: It is suggested that the case presented as an unusual SN variation, which may affect the success of local anesthesia in invasive procedures to the medial part of the foot and could be considered in the evaluation of sensory loss after anteromedial surgical approach to the ankle, should be included in the classification of the cutaneous innervation pattern of the foot.

Ultrasound assessment of medial crural cutaneous nerve and infrapatellar branch and of the saphenous nerve: establishing a safety zone for preventing nerve injury in knee surgery and injections.

PURPOSE: Our study aimed to illustrate the positional relationship of the two branches of the saphenous nerve: the infrapatellar branch of the saphenous nerve (IPBSN) and medial crural cutaneous nerve (MCCN), as well as the anatomical landmarks using high-resolution ultrasound (HRUS) to help prevent iatrogenic nerve injury. METHODS: We used HRUS to explore the positional relationships among the anatomical landmarks, IPBSN, and MCCN in 40 knees of 20 participants. The distances from these branches to key reference points were recorded. Using the ultrasound caliper mode, we measured the depth from the skin surface to the nerves at four distinct points. RESULTS: The average distances between IPBSN and medial border of patella (MBP) and IPBSN and medial border of patellar ligament (MBPL) were 47 ± 7 mm and 42 ± 9 mm, respectively. MCCN showed mean distances of 94 ± 9 mm and 96 ± 9 mm to MBP and MBPL, respectively. The mean distance from the upper edge of pes anserine to IPBSN at the patellar apex (PA) level was 24 ± 10 mm and to MCCN was 34 ± 9 mm. CONCLUSION: We used high-resolution ultrasound to evaluate IPBSN and MCCN and their positions relative to anatomical landmarks. The study results offer valuable insights into the course of these nerves, which can help establish a safety zone to prevent accidental nerve injuries during knee surgeries and injections.

Diagnostics of infrapatellar saphenous neuralgia-a reversible cause of chronic anteromedial pain following knee surgery.

OBJECTIVES: To evaluate the impact of diagnostic nerve block and ultrasound findings on therapeutic choices and predict the outcome after concomitant surgery in patients with suspected neuropathy of the infrapatellar branch of the saphenous nerve (IPBSN). METHODS: Fifty-five patients following knee surgery with suspicion of IPBSN neuralgia were retrospectively included. Ultrasound reports were assessed for neuroma and postsurgical scarring (yes/no). Responders and non-responders were assigned following anesthetic injection of the IPBSN. The type of procedure (neurectomy/interventional pain procedure/other than nerve-associated therapy) and pain score at initial follow-up were recorded and patients were assigned as positive (full pain relief) or negative (partial/no pain relief) to therapeutic nerve treatment. Factors associated with a relevant visual analog scale (VAS) reduction were assessed using uni- and multivariate logistic regression models and chi-square for quantitative and qualitative variables (p ≤ 0.05). RESULTS: Responders (37/55) more often had an entrapment or an evident neuroma of the IPBSN (97% vs. 6%). A positive Hoffmann-Tinel sign (p = 0.002) and the absence of knee joint instability (p = 0.029) predicted a positive response of the diagnostic nerve block (90%; 26/29). In the follow-up after therapeutic nerve treatment, all patients with full pain relief showed neuromas or entrapment of the IPBSN. Patients negatively responding to therapeutic nerve treatment more frequently showed an additional knee joint instability (25% vs. 4%). CONCLUSION: Selective denervation for neuropathic knee pain is beneficial in selected patients with significant VAS reduction after diagnostic nerve block. Non-responders following diagnostic nerve block but sonographic evidence of IPBSN pathologies need to be evaluated for other causes such as knee joint instability. KEY POINTS: • Sonographic diagnosis of neuroma or entrapment of the IPBSN is frequently seen in patients with anteromedial knee pain and leads to a good response to diagnostic nerve block following knee surgery. • The vast majority of patients with clinical signs of IPBSN neuropathy and response to a diagnostic nerve block sustained full pain relief following therapeutic nerve treatment. • Patients not responding to therapeutic IPBSN treatment have to be evaluated for other causes of anteromedial knee pain such as knee joint instability.

Saphenous nerve schwannoma as a cause of vascular claudication - case report and review of the literature.

Schwannomas are peripheral nerve tumours that are uncommon. They typical present with a palpable mass, pain or neurological changes. We describe a saphenous nerve schwannoma compressing the superficial femoral artery and causing vascular claudication. We also review the literature.

Optimizing the methodology for saphenous nerve somatosensory evoked potentials for monitoring upper lumbar roots and femoral nerve during lumbar spine surgery: technical note.

The demand for intraoperative monitoring (IOM) of lumbar spine surgeries has escalated to accommodate more challenging surgical approaches to prevent perioperative neurologic deficits. Identifying impending injury of individual lumbar roots can be done by assessing free-running EMG and by monitoring the integrity of sensory and motor fibers within the roots by eliciting somatosensory (SEP), and motor evoked potentials. However, the common nerves for eliciting lower limb SEP do not monitor the entire lumbar plexus, excluding fibers from L1 to L4 roots. We aimed to technically optimize the methodology for saphenous nerve SEP (Sap-SEP) proposed for monitoring upper lumbar roots in the operating room. In the first group, the saphenous nerve was consecutively stimulated in two different locations: proximal in the thigh and distal close to the tibia. In the second group, three different recording derivations (10-20 International system) to distal saphenous stimulation were tested. Distal stimulation yielded a higher Sap-SEP amplitude (mean ± SD) than proximal: 1.36 ± 0.9 µV versus 0.62 ± 0.6 µV, (p < 0.0001). Distal stimulation evoked either higher (73%) or similar (12%) Sap-SEP amplitude compared to proximal in most of the nerves. The recording derivation CPz-cCP showed the highest amplitude in 65% of the nerves, followed by CPz-Fz (24%). Distal stimulation for Sap-SEP has advantages over proximal stimulation, including simplicity, lack of movement and higher amplitude responses. The use of two derivations (CPz-cCP, CPz-Fz) optimizes Sap-SEP recording.

Unusual case of the saphenous plexus in the thigh and why we should have borne this variation in mind.

Detailed knowledge of the anatomy and different variations of the saphenous nerve could be of great importance not only to anatomists but also to clinicians. There are very few studies of saphenous nerve morphology in thigh. Most of the reported variations of this nerve concern the infrapatellar branch. In contrast, a saphenous plexus has been described in only one case. Herein, we present an unusual case of unilateral saphenous plexus formation in the right thigh found during routine anatomical dissection of a 69-year-old male Caucasian cadaver. We also present a brief discussion of the saphenous plexus and emphasize its potential clinical implications.

Anatomical variation of the saphenous nerve path: A case report.

INTRODUCTION: The saphenous nerve has great importance on the sensitivity of the lower limb. In its normal course, it enters the adductor canal and travels under the sartorius muscle, on the medial side of the thigh. METHODS: The anatomical variation was found accidentally during routine cadaveric dissection of the thigh at the Human Anatomy Laboratory of the Department of Morphophysiology of the Faculty of Medical Sciences of Minas Gerais (FCMMG). RESULTS: A different pattern of path of the saphenous nerve was found, which appears to perforate the sartorius muscle. DISCUSSION: Complaints of pain in the lower limbs are highly prevalent in the adult population. Saphenous neuropathy is a pathological entity that is associated with such a clinic and may have compression or trauma as its etiology. In the context of compression, it can be caused due to the unusual nerve path, as described in the present study. In trauma, knowledge of this variation is important to prevent iatrogenic damage to nervous tissue during surgical procedures. CONCLUSION: The anatomic variation presented may be related to the symptom of pain in the lower limbs and is also relevant in the surgical context, in order to prevent complications.

Ultrasound-guided pulsed radiofrequency of the saphenous nerve in a complex regional pain syndrome patient with lower limb pain.

Complex regional pain syndrome is a painful and debilitating syndrome in which the patient presents with disabling pain, edema, and/or vasomotor or sudomotor abnormalities. The mechanism is complex and not well understood. There is no definitive treatment for the condition yet. Pulsed radiofrequency is a minimally invasive, minimal destructive, and safe intervention. It can be used for neuropathic pain. A 40-year-old man with complex regional pain syndrome complained of intractable pain of the lower limb secondary to injury to the saphenous nerve due to a third-degree burn. Conventional medications, epidural block, and sympathetic nerve block provided temporary relief. We performed pulsed radiofrequency of the saphenous nerve for the management of lower limb pain, and the symptoms remained under control at 3 months. To the best of our knowledge, this is the first application of ultrasound-guided pulsed radiofrequency of the saphenous nerve for the management of complex regional pain syndrome.

Adductor canal block with or without added magnesium sulfate following total knee arthroplasty: a multi-arm randomized controlled trial.

PURPOSE: Postoperative analgesia following total knee arthroplasty (TKA) often includes intrathecal opioids, periarticular injection (PAI) of local anesthetic, systemic multimodal analgesia, and/or peripheral nerve blockade. The adductor canal block (ACB) provides analgesia without muscle weakness and magnesium sulphate (MgSO4) may extend its duration. The purpose of this trial was to compare the duration and quality of early post-TKA analgesia in patients receiving postoperative ACB (± MgSO4) in addition to standard care. METHODS: Elective TKA patients were randomized to: 1) sham ACB, 2) ropivacaine ACB, or 3) ropivacaine ACB with added MgSO4. All received spinal anesthesia with intrathecal morphine, intraoperative PAI, and multimodal systemic analgesia. Patients and assessors remained blinded to allocation. Anesthesiologists knew whether patients had received sham or ACB but were blinded to MgSO4. The primary outcome was time to first analgesic (via patient-controlled analgesia [PCA] with iv morphine) following ACB. Secondary outcomes were morphine consumption, side effects, visual analogue scale pain scores, satisfaction until 24 hr postoperatively, and length of stay. RESULTS: Of 130 patients, 121 were included. Nine were excluded post randomization: four were protocol violations, three did not meet inclusion criteria, and two had severe pain requiring open label blockade. There were no differences in the median [interquartile range] time to first PCA request: sham, 310 min [165-550]; ropivacaine ACB, 298 min [120-776]; and ropivacaine ACB with MgSO4, 270 min [113-780] (P = 0.96). Similarly, we detected no differences in resting pain, opioid consumption, length of stay, or associated side effects until 24 hr postoperatively. CONCLUSION: We found no analgesic benefit of a postoperative ACB, with or without added MgSO4, in TKA patients undergoing spinal anesthesia and receiving intrathecal morphine, an intraoperative PAI, and multimodal systemic analgesia. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02581683); registered 21 October 2015.

RéSUMé: OBJECTIF: L'analgésie postopératoire suivant une arthroplastie totale du genou (ATG) inclut souvent des opioïdes intrathécaux, une injection périarticulaire (IPA) d'anesthésique local, une analgésie multimodale systémique, et/ou des blocs des nerfs périphériques. Le bloc du canal des adducteurs (BCA) permet une analgésie sans faiblesse musculaire et le sulfate de magnésium (MgSO4) pourrait prolonger sa durée. L'objectif de cette étude était de comparer la durée et la qualité de l'analgésie post-ATG précoce chez les patients recevant un BCA postopératoire (± MgSO4) en plus des soins standard. MéTHODE: Des patients devant subir une ATG non urgente ont été randomisés à recevoir : 1) un BCA placebo (groupe témoin), 2) un BCA avec ropivacaïne, ou 3) un BCA avec ropivacaïne et MgSO4. Tous ont reçu une rachianesthésie avec morphine intrathécale, une IPA peropératoire, et une analgésie multimodale systémique. L'allocation a été faite à l'insu des patients et des évaluateurs. Les anesthésiologistes savaient si les patients avaient reçu un placebo ou un BCA, mais n'étaient pas informés de l'ajout ou non de MgSO4. Le critère d'évaluation principal était le temps jusqu'à la première prise d'analgésique (via une analgésie contrôlée par le patient [ACP] avec de la morphine iv) après le BCA. Les critères secondaires comprenaient la consommation de morphine, les effets secondaires, les scores de douleur sur l'échelle visuelle analogue, la satisfaction jusqu'à 24 heures postopératoires, et la durée de séjour. RéSULTATS: Sur 130 patients, 121 ont été inclus. Neuf ont été exclus après la randomisation : quatre l'ont été en raison de violations du protocole, trois ne répondaient pas aux critères d'inclusion, et deux ont ressenti des douleurs graves nécessitant un bloc sans insu. Aucune différence n'a été observée dans le temps médian [écart interquartile] jusqu'à la première demande d'ACP : placebo, 310 min [165-550]; BCA ropivacaïne, 298 min [120-776]; et BCA ropivacaïne avec MgSO4, 270 min [113-780] (P = 0,96). De la même manière, nous n'avons détecté aucune différence dans la douleur au repos, la consommation d'opioïdes, la durée de séjour, ou les effets secondaires associés jusqu'à 24 heures postopératoires. CONCLUSION: Nous n'avons trouvé aucun avantage analgésique à un BCA postopératoire, avec ou sans ajout de MgSO4, chez les patients subissant une ATG sous rachianesthésie et recevant de la morphine intrathécale, une IPA peropératoire, et une analgésie multimodale systémique. ENREGISTREMENT DE L'éTUDE: www.clinicaltrials.gov (NCT02581683); enregistrée le 21 octobre 2015.

Gracilis tendon harvest may lead to both incisional and non-incisional saphenous nerve injuries.

PURPOSE: The purpose of this study was to map saphenous nerve injuries after gracilis tendon harvest, with the aim of contributing knowledge that makes it possible to prevent these injuries. METHODS: Twenty-two cadaver limbs were used. Three were dissected to examine fascial structures between the saphenous nerve and the gracilis tendon. In 19 limbs, the gracilis tendon was harvested according to standard operative routine. The saphenous nerve was subsequently exposed by dissection and injuries were recorded. RESULTS: A well-defined sub-sartorial fascial layer separated the saphenous nerve from the gracilis tendon. Incisional injuries involving either a medial cutaneous crural branch or the infrapatellar branch were found in 14 of the 19 cases. Non-incisional injuries affecting the sartorial branch of the saphenous nerve (to conform to most surgical literature, we use the term 'sartorial branch' to denote the continuation of the saphenous nerve after departure of the infrapatellar branch) were found in six cases located 5-8 cm proximal and posterior to the gracilis tendon insertion on tibia. The fascia separating the saphenous nerve from the gracilis tendon had been perforated in relation to all non-incisional injuries. CONCLUSIONS: Small subcutaneous branches of the saphenous nerve are at risk of injury from the incision, while the sartorial branch is at risk outside the incision area. Descriptions of the location of non-incisional injuries have not been published before and are of clinical relevance, as they can contribute to the prevention of saphenous nerve injuries during gracilis tendon harvest.