Lateral Plantar Nerve Research Articles

Branching patterns of medial and inferior calcaneal nerves around the tarsal tunnel.

ObjectiveTo demonstrate the bifurcation pattern of the tibial nerve and its branches.MethodsEleven legs of seven fresh cadavers were dissected. The reference line for the bifurcation point of tibial nerve branches was an imaginary horizontal line passing the tip of the medial malleolus. The distances between the reference line and the bifurcation points were measured. The bifurcation branching patterns were categorized as type I, the pattern in which the medial calcaneal nerve (MCN) branched most proximally; type II, the pattern in which the three branches occurred at the same point; and type III, in which MCN branched most distally.ResultsThere were seven cases (64%) of type I, three cases (27%) of type III, and one case (9%) of type II. The median MCN branching point was 0.2 cm (range, -1 to 3 cm). The median bifurcation points of the lateral plantar nerves and inferior calcaneal nerves was -0.6 cm (range, -1.5 to 1 cm) and -2.5 cm (range, -3.5 to -1 cm), respectively.ConclusionMCN originated from the tibial nerve in most cases, and plantar nerves were bifurcated below the medial malleolus. In all cases, inferior calcaneal nerves originated from the lateral plantar nerve. These anatomical findings could be useful for performing procedures, such as nerve block or electrophysiologic studies.

Sex differences in the branching position of the nerve to the abductor digiti minimi muscle: an anatomical study of cadavers.

BackgroundThe nerve to the abductor digiti minimi muscle (ADMM nerve) is the first branch of the lateral plantar nerve or originates directly from the posterior tibial nerve. Damage to the ADMM nerve is a cause of heel pain and eventually results in ADMM atrophy. It is known that ADMM atrophy occurs more often in females than in males, and the reason remains unclear. This study aimed to explore sex differences in the branching pattern, position, and angle of the ADMM nerve.MethodsForty-two cadavers (20 males, 22 females) were dissected at Aichi Medical University between 2011 and 2015. Cases of foot deformity or atrophy were excluded and 67 ft (30 male, 37 female) were examined to assess the branching pattern, position, and angle of the ADMM nerve.ResultsThe branching positions of the ADMM nerve were superior to the malleolar–calcaneal axis (MCA) in 37 ft (55 %), on the MCA in 10 ft (15 %), and inferior to the MCA in 20 ft (30 %). There was no case among male feet in which the ADMM nerve branched inferior to the MCA, whereas this pattern was observed in 19 of 37 female feet (51 %). The branching position of the ADMM nerve was significantly closer to the MCA in female feet than in male feet. There were no significant sex differences in the branching pattern and angle of the ADMM nerve.ConclusionsThe ADMM nerve sometimes branches off inferior to the MCA in females, but not in males. This difference may be the reason for the more frequent occurrence of ADMM atrophy in females than in males.

Hindlimb lameness associated with proximal suspensory desmopathy and injury of the accessory ligament of the suspensory ligament in five horses

SummaryThe accessory ligament of the hindlimb suspensory ligament arises from the plantar aspect of the calcaneus and fourth tarsal bones and blends with the suspensory ligament in the proximal aspect of the metatarsus. The accessory ligament of the suspensory ligament of both hindlimbs of 12 mature horses, with no history of hindlimb lameness, was assessed ultrasonographically. The ligament comprised linear parallel echoes which were consistently shorter than those of the lateral digital flexor tendon; the dorsal and plantar borders were parallel. Lameness associated with injury of the accessory ligament of the suspensory ligament was identified in 6 of 8 lame hindlimbs of 5 horses, unilaterally in 4 horses and bilaterally in one horse. In all horses there was concurrent proximal suspensory desmopathy. There was localised oedematous swelling on the distal medial aspect of the chestnut extending distally in 2 horses. Lameness was best identified when the horses were ridden. Perineural analgesia of the deep branch of the lateral plantar nerve abolished lameness in 3 horses but perineural analgesia of the tibial nerve was required to abolish lameness in the hindlimb with injury of the accessory ligament of the suspensory ligament in 2 horses. Injury of the accessory ligament of the suspensory ligament was characterised by marked decrease in echogenicity of the ligament and loss of parallel alignment of the linear echoes, which were shorter than normal in longitudinal images.

The origin and branching of medial calcaneal nerve in newborn foetuses

IntroductionEntrapment of the medial heel region nerves is often mentioned as a possible cause of heel pain. Some authors have suggested that the medial calcaneal nerve (MCN) may be involved in such heel pain. The aim of the present study is to describe the variations of the origin of the medial calcaneal nerve and its branching patterns in the medial aspect of the calcaneus which establishes an anatomical guide for diagnosis and therapy of some tarsal region diseases. Material and methodsThe formation and course of the MCN were traced to its branches in the distal ankle with the use of 4.8 X stereomicroscope (Carl-Zeis) or 28 X loop magnification for dissections of 36 newborn feet of formalin fixed cadavers. ResultsThe MCN originated from the tibial nerve (TN) in 61.1% and from the lateral plantar nerve (LPN) 16.7%, bilaterally. It branches from the TN on the right side and from the LPN on the left side in 11.1%, from the LPN on the right side and from the TN on the left side in 11.1%.The MCN consisted of 1 terminal branch in 3 out of 36 feet, 2 terminal branches in 28 out of 36, and 3 terminal branches in 5 out of 36. DiscussionThe course and the origin of MCN on the medial aspect of the heel and its terminal branches were quite different. These variabilities will enable the surgeon to find and preserve the MCN and its terminal branches.

Les syndromes canalaires au pied

The entrapment neuropathy of the foot is very rare. The most famous is the tarsal tunnel syndrome. It results of the compression of the tibial nerve or its two terminal branches, the medial and lateral plantar nerves, when it passes beneath the flexor retinaculum at the ankle. It is not truly an entrapment neuropathy as it is in the carpal tunnel syndrome. Injuries and traumatisms are frequently the causes. The existence of true idiopathic forms is disputed. The diagnosis is difficult. The electrophysiological examination is by far less performing than for the median nerve at the carpal tunnel. The other syndroms are even rarer. It may be the terminal branches of the tibial nerve: medial and lateral plantar nerves, the calcanean nerves, the distal extremities of the fibular nerves. The Morton neuroma may be associated to these syndromes.

In vivodiffusion characteristics following perineural injection of the deep branch of the lateral plantar nerve with mepivacaine or iohexol in horses

Hindlimb proximal suspensory desmopathy is a common injury of sport horses but diagnosis can be difficult because diagnostic analgesia of the region lacks specificity. Perineural analgesia of the deep branch of the lateral plantar nerve (DBLPN) has been proposed as a more specific method of isolating pain of the proximal aspect of the suspensory ligament but the technique has not been evaluated in vivo. To determine the extent of diffusion of contrast medium and mepivacaine following DBLPN analgesia using a single-needle injection technique and to determine if there is inadvertent involvement of the tarsal sheath and/or tarsometatarsal (TMT) joint using this technique. In vivo experimental study. Perineural injection of the DBLPN was performed in 16 limbs with 3 ml of either mepivacaine hydrochloride or positive contrast medium. Contrast medium-injected limbs were radiographed 5, 15, and 30 min post injection and diffusion characteristics were described. In mepivacaine-injected limbs, synovial fluid from the TMT joint was obtained 10 and 20 min post injection and mepivacaine concentrations were analysed. At 5, 15 and 30 min post injection, the contrast medium extended, on average, 19.6, 20.6 and 21.0 mm proximal and 38.0, 43.5 and 51.9 mm distal to the injection site, respectively. Three of 8 (37.5%) limbs had evidence of contrast medium in the tarsal sheath. Two of 8 (25%) limbs had mepivacaine concentrations within the TMT joint sufficient to produce analgesia (>300 mg/l) at 10 min post injection. Contrast medium diffused further in a distal direction than in a proximal direction. Analgesia of the DBLPN can result in inadvertent involvement of the tarsal sheath and/or TMT joint.

Reconstruction of the great toe using a pedicled medial plantar flap with anterograde venous drainage

Reconstruction of the great toe defect is difficult. The most distal point of the rotation arc of a retrograde-flow medial plantar flap is the plantar side of the proximal phalanx. The purpose of this report was to present a new procedure that extends the rotation arc of this flap. Results of anatomic study and application in two patients were presented. An anatomical study was conducted on 10 freshly frozen cadavers to determine the rotation arc of the medial plantar flap based distally on the lateral plantar vessels. To enable anterograde venous drainage, two accompanying veins of the vascular pedicle were separated and anastomosed to each other. This surgical procedure was implemented in two clinical cases with the great toe defect. The maximum size of the elevated flap was 4 × 7 cm. The status of venous congestion of the flap was determined using the blood glucose measurement index. We confirmed that the rotation arc of the medial plantar flap based distally on the lateral plantar vessels could reach the tip of the great toe, preserving all lateral plantar nerves and plantar metatarsal arteries. In the two cases, the congestion of the flap improved with anterograde venous drainage and the flaps survived completely. A pedicled medial plantar flap with anterograde venous drainage may be a useful alternative option for the reconstruction of relatively large great toe defects.

Is anaesthesia of the deep branch of the lateral plantar nerve specific for the diagnosis of proximal metatarsal pain in the horse?

To investigate the specificity of anaesthesia of the deep branch of the lateral plantar nerve (DB-LPN). Twenty horses had DB-LPN anaesthesia performed by a single injection technique as part of a lameness investigation. The mechanical nociceptive threshold (NT) was measured using a handheld force meter at six points on the lateral aspect of the limb: before diagnostic anaesthesia (T0), and at 15 (T15) and 30 (T30) minutes post anaesthesia. Paired t-tests were performed and significance was set at p <0.05. In addition, ten cadaveric limbs were injected with 2.5 ml new methylene blue solution using a single injection technique to evaluate the extent of dye diffusion within the proximal metatarsal region. Compared with T0, there was a significant decrease in NT for all points combined at T15 (p = 0.008) and also at T30 (p = 0.007). There was a significant decrease in NT at T15 on the lateral third metatarsal bone (p = 0.012). At T30 there was a significant decrease in NT at the lateral sesamoid (p = 0.007), lateral third metatarsal bone (p = 0.031), and mid metatarsus (p = 0.033). Four out of 20 horses had a NT greater than 10 N at the lateral heel bulb at T30. In the cadaveric limbs, the total diffusion distance for all limbs (mean ± SD) was 70.4 ± 20.5 mm. Dye surrounded the DB-LPN in all limbs and the lateral plantar nerve (LPN) in nine out of 10 limbs. Concurrent anaesthesia of the LPN is likely to occur when DB-LPN anaesthesia is performed using a single injection technique.

The features and diagnostic value of electrophysiological examination in tarsal tunnel syndrome

Objective To investigate the diagnostic value of electrophysiological examination for tarsal tunnel syndrome (TTS).Methods Motor nerve conduction velocity (MCV),sensory nerve conduction velocity (SCV),F wave and electromyographic measurements were carried out with 26 clinically suspected TTS patients.Results Of the 26,22 patients were unilaterally affected and 4 were bilaterally affected,so 30 tarsal tunnels in total were affected.All received electrophysiological examination.Of the 30 affected tarsal tunnels,abnormal MCV was detected in 28 of the posterior tibial nerves (93.3％),while abnormal SCV was detected in 27 medial plantar nerves (90％) and 24 lateral plantar nerves (80％).Needle electromyography of 156 targeted foot muscles detected abnormal spontaneous potentials in 90 of them (57.7％),giant potential in 12 muscles (7.7％) and decreased recruitment in 76 (48.7％).Conclusions The distal posterior tibial nerve is impaired in TTS,presenting axonal damage in an electrophysiological examination.Such examinations should have an important role in the diagnosis and differential diagnosis of TTS. Key words: Tarsal tunnel syndrome; Electrophysiological examination; Feet

Oedema of the abductor digiti quinti muscle due to subacute denervation: Report of two cases

The clinical presentation of abductor digiti quinti (ADQ) denervation is often non-specific. The diagnosis is generally clinical and may be easily missed. This case report of two patients describes the magnetic resonance imaging (MRI) finding of unilateral oedema and fatty infiltration isolated to the ADQ. A 36-year old woman who presented with laterally located left foot pain was initially diagnosed as having plantar fasciitis. An MRI scan arranged due to the unusual site of the pain showed increased signal intensity within the ADQ muscle on T1 and T2 images indicating fatty infiltration. Short tau inversion recovery (STIR) images showed hyperintensity of the ADQ indicating oedema. The MRI scan of a 45-year old man who presented with a three month history of left heel pain revealed similar findings. These MRI appearances indicate subacute denervation, which, when involving solely the ADQ muscle suggests entrapment of the first branch of the lateral plantar nerve. Consideration of this imaging finding when examining MRI scans of patients with non-specific heel pain has the potential to facilitate diagnosis.

Distal Entrapment of the Lateral Plantar Nerve Beyond the Tarsal Tunnel Revealed by Electrodiagnostic Study: A Case Report

PM&RVolume 5, Issue 9S p. S232-S232 Musculoskeletal and Sports Medicine Distal Entrapment of the Lateral Plantar Nerve Beyond the Tarsal Tunnel Revealed by Electrodiagnostic Study: A Case Report Lawrence P. Lai MD, MS, Lawrence P. Lai MD, MS Rutgers: New Jersey Medical School, Newark, NJ, United StatesSearch for more papers by this authorMooyeon Oh-Park MD, MS, Mooyeon Oh-Park MD, MS Rutgers: New Jersey Medical School, Newark, NJ, United StatesSearch for more papers by this author Lawrence P. Lai MD, MS, Lawrence P. Lai MD, MS Rutgers: New Jersey Medical School, Newark, NJ, United StatesSearch for more papers by this authorMooyeon Oh-Park MD, MS, Mooyeon Oh-Park MD, MS Rutgers: New Jersey Medical School, Newark, NJ, United StatesSearch for more papers by this author First published: 17 September 2013 https://doi.org/10.1016/j.pmrj.2013.08.366Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue9SSeptember 2013Pages S232-S232 RelatedInformation

Sonographic Visualization of the First Branch of the Lateral Plantar Nerve (Baxter Nerve)

The primary purpose of this investigation was to document the ability of high-resolution sonography to accurately identify the first branch of the lateral plantar nerve (FBLPN) using sonographically guided perineural injections in an unembalmed cadaveric model. single experienced operator completed sonographically guided perineural FBLPN injections in 12 unembalmed cadaveric specimens (6 right and 6 left) obtained from 10 donors (5 male and 5 female) aged 47 to 95 years (mean, 71 years) with an average body mass index of 24.2 kg/m(2) (range, 17.2-31.6 kg/m(2)). All injections were completed using 22-gauge, 38-mm stainless steel needles to deliver 1 mL of 50% diluted colored latex adjacent to the FBLPN in the abductor hallucis-quadratus plantae (AH-QP) interval. Six injections were completed using a cart-based ultrasound (US) machine and a 17-5-MHz transducer, and 6 were completed using a portable US machine and a 12-3-MHz transducer. Nerve conspicuity was graded on a 4-point scale (1, poor; 4, excellent). After a minimum of 24 hours, study coinvestigators dissected each specimen to assess injectate placement. All 12 injections accurately placed latex onto the FBLPN within the AH-QP interval, with 11 of 12 (91%) resulting in complete nerve coverage. Proximal latex overflow to the lateral plantar nerve occurred in 82% of cases (10 of 12). The average distance between the plantar fascia and injected latex was 1.2 cm (range, 1.0-1.75 cm). No vascular injury was seen in any specimen. The average nerve conspicuities were 3.7 (range, 3-4) using the cart-based US machine and 1.8 (range, 1-4) using the portable US machine. Sonographic visualization of the FBLPN in the AH-QP interval is feasible and should be considered for diagnostic and therapeutic purposes in patients presenting with chronic or atypical heel pain syndromes. Further clinical experience should refine the role of FBLPN sonography and explore the utility of sonographically guided diagnostic and therapeutic FBLPN perineural injections.

Foot Orgasm Syndrome: A Case Report in a Woman

Spontaneous orgasm triggered from inside the foot has so far not been reported in medical literature. The study aims to report orgasmic feelings in the left foot of a woman. A woman presented with complaints of undesired orgasmic sensations originating in her left foot. In-depth interview, physical examination, sensory testing, magnetic resonance imaging (MRI-scan), electromyography (EMG), transcutaneous electrical nerve stimulation (TENS), and blockade of the left S1 dorsal root ganglion were performed. The main outcomes are description of this clinical syndrome, results of TENS application, and S1 dorsal root ganglion blockade. Subtle attenuation of sensory amplitudes of the left suralis, and the left medial and lateral plantar nerve tracts was found at EMG. MRI-scan disclosed no foot abnormalities. TENS at the left metatarso-phalangeal joint-III of the left foot elicited an instant orgasmic sensation that radiated from plantar toward the vagina. TENS applied to the left side of the vagina elicited an orgasm that radiated to the left foot. Diagnostic blockade of the left S1 dorsal root ganglion with 0.8 mL bupivacaine 0.25 mg attenuated the frequency and intensity of orgasmic sensation in the left foot with 50% and 80%, respectively. Additional therapeutic blockade of the same ganglion with 0.8 mL bupivacaine 0.50 mg combined with pulsed radiofrequency treatment resulted in a complete disappearance of the foot-induced orgasmic sensations. Foot orgasm syndrome (FOS) is descibed in a woman. Blockade of the left S1 dorsal root ganglion alleviated FOS. It is hypothesized that FOS, occurring 1.5 years after an intensive care emergency, was caused by partial nerve regeneration (axonotmesis), after which afferent (C-fiber) information from a small reinnervated skin area of the left foot and afferent somatic and autonomous (visceral) information from the vagina on at least S1 spinal level is misinterpreted by the brain as being solely information originating from the vagina.

Sonographically Guided Deep Plantar Fascia Injections

To determine the distribution of sonographically guided deep plantar fascia injections in an unembalmed cadaveric model. A single experienced operator completed 10 sonographically guided deep plantar fascia injections in 10 unembalmed cadaveric specimens (5 right and 5 left) obtained from 6 donors (2 male and 4 female) aged 49 to 95 years (mean, 77.5 years) with a mean body mass index of 23.2 kg/m(2) (range, 18.4-26.3 kg/m(2)). A 12-3-MHz linear array transducer was used to direct a 22-gauge, 38-mm stainless steel needle deep to the plantar fascia at the anterior aspect of the calcaneus using an in-plane, medial-to-lateral approach. In each case, 1.5 mL of 50% diluted colored latex was injected deep to the plantar fascia. After a minimum of 72 hours, study coinvestigators dissected each specimen to assess injectate placement. All 10 injections accurately placed latex adjacent to the deep side of the plantar fascia at the anterior calcaneus. However, the flexor digitorum brevis (FDB) origin from the plantar fascia variably limited direct latex contact with the plantar fascia, and small amounts of latex interdigitated with the FDB origin in 90% (9 of 10). In all 10 specimens, latex also covered the traversing first branch of the lateral plantar nerve (FBLPN, ie, Baxter nerve) between the FDB and quadratus plantae muscles. No latex was found in the plantar fat pad or plantar fascia in any specimen. Sonographically guided deep plantar fascia injections reliably deliver latex deep to the plantar fascia while avoiding intrafascial injection. However, the extent of direct plantar fascia contact is variable due to the intervening FDB. On the contrary, the traversing FBLPN is reliably covered by the injection. Deep plantar fascia injections may have a role in the management of refractory plantar fasciitis, particularly following failed superficial perifascial or intrafascial injections, in cases of preferential deep plantar fascia involvement, or when entrapment/irritation of the distal FBLPN is suspected.

Lateral heel pain

Baxter’s nerve originates from the lateral plantar nerve near the trifurcation of the posterior tibial nerve at the level of the medial malleolus [1–5]. It may also infrequently arise directly from the tibial nerve or at the common origin of the medial calcaneal nerve [5]. It then travels between the abductor hallucis and quadratus plantae muscles before turning laterally to pass anterior to the medial calcaneal tuberosity. From here, it courses between the quadratus plantae and flexor digitorum brevis muscle before innervating the abductor digiti minimi muscle [3, 4]. Two key sites have been identified for Baxter’s nerve entrapments. The nerve is often compressed between the quadratus plantae and abductor hallucis muscle as it turns laterally. It is also commonly compressed as it passes anteriorly to the medial calcaneal tuberosity [1–3]. Compression occurs from either a hypertrophied abductor hallucis muscle, as often seen in long-distance runners, by thickened plantar fascia, inferior calcaneal enthesophytes, or as a result of altered foot biomechanics and internal derangements leading to nerve stretching from the hypermobile foot [2, 3, 6, 7]. Diagnosis is achieved through the use of MRI, which is the preferred imaging modality [8, 9]. T1-weighted spinecho or fast spin-echo sequences can characterize the nerve’s anatomy along with its surrounding structures, while T2-weighted spin-echo or fast spin-echo sequences allow for better identification of edema within the nerve and its surrounding structures [8, 9]. As Baxter’s nerve provides some motor innervations to the flexor digitorum brevis, quadratus plantae and abductor digiti minimi muscles, MRI changes of a denervated muscle can occur as early as 4 days after a traumatic nerve injury [9]. Neurogenic edema may be seen in the subacute phase while muscular atrophy with fatty infiltration may be seen in the chronic phase [9]. One of the hallmark features of Baxter’s neuropathy is fatty infiltration and atrophy of the abductor digiti minimi muscle as seen in Fig. 1 of the case presentation [2–4, 6, 7]. One may also find abductor hallucis muscle hypertrophy, a calcaneal enthesophyte (Fig. 2 of the case presentation), surrounding soft tissue edema (Fig. 1 and Fig. 3 of the case presentation), and potential cofounding signs of plantar fasciitis on MRI [7]. One study suggests that Baxter’s neuropathy may account for an upward of 20 % of heel pain [3]. As Baxter’s nerve provides sensory innervation to the long plantar ligament and calcaneal periosteum, patients with Baxter’s neuropathies typically present with medial heel pain that is often difficult to distinguish from plantar fasciitis [2, 3, 6, 7]. Other symptoms may include paresthesia along the lateral third of the sole of the foot and the characteristic abductor digiti minimi muscle weakness [2, 3]. The differential diagnosis includes plantar fasciitis, Achilles tendinosis, painful heel pad syndrome, bone tumors, heel spur fracture, calcaneal stress fracture, and bursitis among others [3, 5]. Overall, conservative treatment is often sufficient for Baxter’s neuropathy and is nearly identical to the treatment The case presentation can be found at doi: 10.1007/s00256-013-1598-3

Higher division of the tibial nerve in the leg: gross anatomical study with clinical implications.

Tibial nerve is a branch of the sciatic nerve and it is the main nerve innervating the muscles of the back of the leg. The tibial nerve divides into medial and lateral plantar nerves. The level of division may be important for surgical purpose. The main aim of the present study was to observe the exact level of division of the tibial nerve and discuss its clinical implications. A total of 20 cadaveric limbs (irrespective of left or right side) were taken randomly. The posterior compartment of the thigh and leg was dissected to trace the tibial nerve and its branches. The specimens were subjected to measurements with respect to an arbitrary horizontal line passing through tip of medial malleolus and the calcaneum. All the specimens were photographed. In 5 cases (25%), the tibial nerve divided deep to the flexor retinaculum. In 15 cases (75%) cases, the tibial nerve divided at a distance of 3.5 cm - 6.5 cm (average 5 cm) above the medial malleolus. The tibial nerve and its divisions are important for performing successful nerve blocks and insertion of plates while treating fractures. Variations may account for the various discrepancies between the electromyographic tests and clinical tests.

Entrapment of the Lateral Plantar Nerve Distal to the Tarsal Tunnel: A Case Report

Tibial nerve entrapment is a common cause of foot pain. Identifying the location of the entrapment may be difficult. This case report describes the electrodiagnosis of the lateral plantar nerve branch of the tibial nerve in a 50 year-old woman who failed to respond to the local steroid injection for plantar fasciitis and subsequently a tarsal tunnel release. The etiology of the nerve entrapment is discussed as well as the role of electrodiagnostic studies to locate the nerve entrapment. This case highlights the role of meticulous clinical evaluation and electrodiagnosis for the diagnosis of this challenging condition and a simple in-office treatment to reduce patient’s symptoms.

Fixation of the Achilles Tendon Insertion Using Suture Button Technology

Background: In the operative treatment of Achilles insertional tendinopathy, no guidelines exist concerning which form of fixation of the Achilles tendon insertion is superior. Hypothesis: Transcalcaneal drill pin passage does not place any major plantar structures at risk, and the addition of a Krackow stitch and suture button to the fixation technique provides a significant increase in ultimate load to failure in Achilles tendon insertional repairs. Study Design: Controlled laboratory study. Methods: The Achilles tendon insertions in 6 fresh-frozen cadaveric ankles were detached, and transcalcaneal drill pins were passed. Plantar dissection took place to evaluate the drill pin relationship to the plantar fascia, lateral plantar nerve and artery, flexor digitorum longus tendon, and master knot of Henry. The Achilles tendons were then repaired with a double-row suture anchor construct alone or with a suture button and Krackow stitch added to the double-row suture anchor construct. The repairs were then tested to maximum load to failure at 20 mm/min. The mode of failure was recorded, and the mean maximum load to failure was assessed using the Student t test for distributions with equal variance. Results: Transcalcaneal drill pin passage did not place any selected anatomic structures at risk. The mean maximum load to failure for the suture bridge group was 239.2 N; it was 391.4 N for the group with the suture button (P = .014). The lateral plantar artery was the structure placed at greatest risk from drill pin placement, with a mean distance of 22.7 mm (range, 16.5-29.2 mm) between the pin and artery. Conclusion: In this laboratory study, transcalcaneal drill pin passage appeared to be anatomically safe, and the use of suture button technology with a Krackow stitch for Achilles tendon insertional repair significantly increased repair strength. Clinical Relevance: Achilles tendon insertional repair with suture button fixation and a Krackow stitch may facilitate the earlier institution of postoperative rehabilitation and improve clinical outcomes.

The influence of a continuous rate infusion of dexmedetomidine on the nociceptive withdrawal reflex and temporal summation during isoflurane anaesthesia in dogs

ObjectiveTo examine the influence of a low dose dexmedetomidine infusion on the nociceptive withdrawal reflex and temporal summation in dogs during isoflurane anaesthesia. Study designProspective experimental blinded cross-over study. AnimalsEight healthy mixed breed dogs, body weight Mean ± SD 26.5 ± 8.4 kg and age 25 ± 16 months. MethodsAnaesthesia was induced with propofol and maintained with isoflurane (Fe′ISO 1.3%) delivered in oxygen and air. After stabilization, baseline recordings (time 0) were obtained, then a dexmedetomidine bolus (1 μg kg−1 IV) followed by a continuous rate infusion (1 μg kg−1 hour−1) or saline placebo were administered. At times 10, 30 and 60 minutes after the initial bolus, electrical stimulations of increasing intensity were applied over the lateral plantar digital nerve, and administered both as single and as repeated stimuli. The resulting reflex responses were recorded using electromyography. Data were analysed using a multivariable linear regression model and a Kruskal Wallis test for single stimulation data, and repeated measures anova and paired t-test for repeated stimulation data. ResultsThe AUC for the stimulus-response curves after single stimulation were similar for both treatments at time 0. At times 10, 30 and 60 the AUCs for the stimulus-response curves were significantly lower with dexmedetomidine treatment than with placebo. Temporal summation was evident in both treatments at times 0, 10, 30 and 60 starting from a stimulation intensity of 10 mA. The magnitude of temporal summation was smaller in dexmedetomidine than in placebo treated dogs at time 10, 30 and 60, but not at time 0. ConclusionsDuring isoflurane anaesthesia, low dose dexmedetomidine suppresses the nociceptive reflex responses after single and repeated electrical stimulation. Clinical relevanceThis experimental study confirms previous reports on its peri-operative efficacy under clinical conditions, and further indicates that dexmedetomidine might reduce the risk of post-operative chronic pain development.

Normal and sonographic anatomy of selected peripheral nerves. Part III: Peripheral nerves of the lower limb.

The ultrasonographic examination is currently increasingly used in imaging peripheral nerves, serving to supplement the physical examination, electromyography and magnetic resonance imaging. As in the case of other USG imaging studies, the examination of peripheral nerves is non-invasive and well-tolerated by patients. The typical ultrasonographic picture of peripheral nerves as well as the examination technique have been discussed in part I of this article series, following the example of the median nerve. Part II of the series presented the normal anatomy and the technique for examining the peripheral nerves of the upper limb. This part of the article series focuses on the anatomy and technique for examining twelve normal peripheral nerves of the lower extremity: the iliohypogastric and ilioinguinal nerves, the lateral cutaneous nerve of the thigh, the pudendal, sciatic, tibial, sural, medial plantar, lateral plantar, common peroneal, deep peroneal and superficial peroneal nerves. It includes diagrams showing the proper positioning of the sonographic probe, plus USG images of the successively discussed nerves and their surrounding structures. The ultrasonographic appearance of the peripheral nerves in the lower limb is identical to the nerves in the upper limb. However, when imaging the lower extremity, convex probes are more often utilized, to capture deeply-seated nerves. The examination technique, similarly to that used in visualizing the nerves of upper extremity, consists of locating the nerve at a characteristic anatomic reference point and tracking it using the “elevator technique”. All 3 parts of the article series should serve as an introduction to a discussion of peripheral nerve pathologies, which will be presented in subsequent issues of the “Journal of Ultrasonography”.