Nerve block of the infrapatellar branch of the saphenous nerve in knee arthroscopy: a prospective, double-blinded, randomized, placebo-controlled trial

BACKGROUND

With the rising use of outpatient knee arthroscopy over the past decade, interest in peripheral nerve blocks during arthroscopy has increased. Femoral nerve blocks are effective but are associated with an inherent risk of the patient falling postoperatively because of quadriceps weakness. We studied blocks of the infrapatellar branch of the saphenous nerve, which produce analgesia in the knee that is similar to that resulting from a femoral nerve block but without associated quadriceps weakness.

METHODS

Thirty-four patients were enrolled into each arm of this prospective, randomized, double-blinded trial comparing 10 mL of 0.25% bupivacaine used as a block of the infrapatellar branch of the saphenous nerve with a placebo during simple knee arthroscopy. Immediate outcome measures included Numeric Rating Scale (NRS) pain scores (0 to 10 points), mobility and discharge times, opioid usage, subjective adverse side effects, and forty-eight-hour anesthesia recovery surveys. Short-term measures included one-week and twelve-week Lysholm knee scores.

RESULTS

No adverse effects or increased quadriceps weakness were observed following use of the nerve block. Improvement in early NRS scores and subjective nausea (p = 0.03) were detected. Patients for whom the block was successful also had improved twelve-week Lysholm knee scores (p = 0.04). No differences in opioid usage, mobility time, forty-eight-hour anesthesia recovery scores, or one-week Lysholm knee scores were found.

CONCLUSIONS

No significant adverse effect or disadvantage was identified for blocks of the infrapatellar branch of the saphenous nerve used in simple knee arthroscopy. In addition to decreased early NRS scores and nausea, blocks of the infrapatellar branch of the saphenous nerve demonstrated potential benefit at twelve weeks after simple knee arthroscopy.

Prevention of accidental exposure in radiotherapy: the risk matrix approach

Knowledge and lessons from past accidental exposures in radiotherapy are very helpful in finding safety provisions to prevent recurrence. Disseminating lessons is necessary but not sufficient. There may be additional latent risks for other accidental exposures, which have not been reported or have not occurred, but are possible and may occur in the future if not identified, analyzed, and prevented by safety provisions. Proactive methods are available for anticipating and quantifying risk from potential event sequences. In this work, proactive methods, successfully used in industry, have been adapted and used in radiotherapy. Risk matrix is a tool that can be used in individual hospitals to classify event sequences in levels of risk. As with any anticipative method, the risk matrix involves a systematic search for potential risks; that is, any situation that can cause an accidental exposure. The method contributes new insights: The application of the risk matrix approach has identified that another group of less catastrophic but still severe single-patient events may have a higher probability, resulting in higher risk. The use of the risk matrix approach for safety assessment in individual hospitals would provide an opportunity for self-evaluation and managing the safety measures that are most suitable to the hospital's own conditions.

[Quality of conventional PAP smears. Quality assessment and motivation for improvement]

The success of cytology in screening programs for cervical cancer is highly dependent on the smear quality. Interdisciplinary projects which evaluate the smear quality and the results of collection devices could be helpful for an improvement and a successful example for quality improvement is presented here. An average of 83% technically adequate and representative smears was documented for 12 million conventional PAP smears; however only an average of 68% technically adequate and representative smears was found for the group of least successful smear takers of all laboratories. This indicates a potential for improvement. Following an interdisciplinary project on smear quality improvement the average rate of representative smears increased from 69 to 83% and in another project this rate remained stable at 86%. Based on 158,411 conventional smears, representative smears were achieved in 92% using Cervex-Brush®, 86% using Szalay Spatula and 82% Cytobrush methods. The combinations of Cytobrush with the Ayre wooden spatula, cotton wool swab or Szalay Spatula achieved 97%, 94% and 92% representative smears, respectively.

The threshold elicited motor response via an in situ femoral nerve catheter predicts analgesia following total knee replacement

Background

Continuous femoral nerve blocks are a part of the multimodal perioperative anesthetic regimen following total knee replacement. Elicitation of a quadriceps muscle contraction (QC) at placement is desirable. We prospectively evaluated the relationship between elicited motor response and threshold current with block success in situ femoral nerve catheters after total knee replacement.

Methods

After Institutional Review Board approval and written informed consent, 100 adults aged ≥18 years, undergoing total knee replacement were studied. The threshold current for an elicited motor response (QC or sartorius muscle contraction [SC]) was recorded during needle insertion, after femoral nerve catheter advancement, and prior to local anesthetic administration on the first postoperative day. Patients were assessed for pinprick sensory anesthesia of the femoral nerve distribution by an observer unaware of the current threshold or evoked motor response at 5-minute intervals for 30 minutes. A successful block was considered a lack of pinprick sensation within 30 minutes.

Results

Ninety patients completed the study. A QC was obtained at needle insertion in 89 and maintained following catheter advancement in 77 subjects. Prior to drug administration a QC was obtained in 66 patients, 13 demonstrated an SC, and 11 had no motor response. QC prior to drug administration had a sensitivity of 0.85 (95% confidence intervals [CI]: 0.75 to 0.92) and a specificity of 0.55 (95% CI: 0.37 to 0.72) for complete femoral nerve block. The specificity of a QC prior to drug administration was greater than at catheter placement (P = 0.006). Compared to the threshold current at catheter placement, 27 patients had a decrease, 60 had an increase, and 3 exhibited no change in the threshold current prior to drug administration (P < 0.01). The median interquartile range (IQR) threshold current in patients that achieved a complete block was 0.56 (0.29 to 0.80) mA compared with 1.1 mA (0.41 to 2.75) mA for incomplete blocks (P < 0.01). The area under the receiver operator characteristics curve for current threshold prior to local anesthetic administration (0.74) was greater than at catheter placement (0.45) (P < 0.001). The intersection of sensitivity and specificity for the minimal threshold current prior to local anesthetic injection was 0.84 mA.

Conclusion

The elicited motor response and current threshold from a stimulating femoral catheter measured prior to local anesthetic injection is an important determinant of the success of femoral nerve block following bolus administration.

Removal of a knotted stimulating femoral nerve catheter using a saline bolus injection

Objective

Stimulating peripheral nerve catheters have become increasingly popular as part of postoperative multimodal analgesia for total knee arthroplasty. We describe a case of a successful nonsurgical removal of a knotted stimulating femoral nerve catheter after saline expansion of the catheter pocket at the bedside.

Case report

A 65-year-old female underwent total knee arthroplasty under combined spinal epidural anesthesia. Postoperatively, a stimulating femoral nerve catheter was placed without complication. The catheter was threaded 12 cm past the needle tip with minimal resistance. Function of the catheter was verified by loss of pinprick sensation in the femoral nerve distribution and excellent analgesic efficacy was achieved. The first attempt at catheter removal was unsuccessful. Thigh flexion and rotation also failed to facilitate catheter removal. The catheter was then left to continuous tension for 6 hours, but further attempts at removal remained unsuccessful. Under ultrasound visualization, 10 mL of saline was injected through the catheter with moderate resistance and without patient discomfort, after which the catheter was removed using minimal tension. The catheter was intact but had a single knot at the distal end of the catheter.

Conclusions

We present a rare case of a knotted stimulating catheter in which the use of a saline bolus to dilate the catheter pocket proved to be successful after other simple methods of catheter removal had failed. Given the simple nature of this technique, it can be attempted at the bedside before more invasive procedures are planned.

Effects of tumor-induced osteomalacia on the bone mineralization process

Fibroblast growth factor 23 (FGF23) overexpression has been identified as a causative factor for tumor-induced osteomalacia (TIO) characterized by hypophosphatemia due to increased renal phosphate wasting, low 1,25(OH)(2)D(3) serum levels, and low bone density. The effects of long-lasting disturbed phosphate homeostasis on bone mineralization are still not well understood. We report on a patient with a 12-year history of TIO, treated with 1,25(OH)(2)D(3) and phosphate, who finally developed hyperparathyroidism with gland hyperplasia before the tumor could be localized in the scapula and removed. During surgery a transiliac bone biopsy was obtained. FGF23 expression in the tumor cells was confirmed by in situ hybridization. Serum FGF23 levels as measured by ELISA were found to be extremely elevated before and decreased after removal of the tumor. Bone histology/histomorphometry and measurement of bone mineralization density distribution using quantitative backscattered electron imaging were performed on the bone biopsy. The data showed important surface osteoidosis and a slightly increased osteoblast but markedly decreased osteoclast number. The mineralized bone volume (-11%) and mineralized trabecular thickness (-18%) were low. The mean degree of mineralization of the bone matrix (-7%), the most frequent calcium concentration (-4.1%), and the amounts of fully mineralized bone (-40.3%) were distinctly decreased, while the heterogeneity of mineralization (+44.5%) and the areas of primary mineralization (+131.6%) were dramatically increased. We suggest that the elevated levels of FGF23 and/or low phosphate concentrations disturb the mineralization kinetics in vivo without affecting matrix mineralization of pre-existing bone packets.

Relationship between ultrasound imaging and eliciting motor response during femoral nerve stimulation

OBJECTIVE

Nerve stimulator-assisted localization of the femoral nerve is well described; however, direct ultrasound imaging of the femoral nerve branches may be challenging. The purpose of this study was to correlate the evoked motor responses obtained by femoral nerve stimulation and the topographic orientation of the femoral nerve branches during ultrasound examinations of the infrainguinal region.

METHODS

Eighty-two patients undergoing total knee replacement were enrolled in this study. A 25-mm, 5- to 10-MHz broadband linear array transducer was used to identify the femoral nerve at the inguinal crease. The medial and lateral aspects of the femoral nerve were stimulated under ultrasound imaging. Twenty cadavers were dissected to support our clinical findings.

RESULTS

A quadriceps contraction was elicited in 1.2% and 96% of the patients when stimulating the medial and lateral aspects of the femoral nerve, respectively. In contrast, a sartorius muscle contraction was elicited in 94% and 0% when stimulating the medial and lateral aspects of the femoral nerve. Our findings during anatomic dissection revealed that the femoral nerve branch to the quadriceps muscle, when compared with the branch to the sartorius muscle, originated laterally in 95% and medially in 5% of the specimens.

CONCLUSIONS

When using out-of-plane ultrasound imaging at the inguinal crease, directing the stimulating needle to the lateral half of the femoral nerve may be associated with a higher probability of encountering the motor branch to the quadriceps muscle.

Evaluation of a Proximal Block Site and the Use of Nerve-Stimulator-Guided Needle Placement for Posterior Tibial Nerve Block

BACKGROUND

Posterior tibial nerve (PTN) block has traditionally been performed in the para-medial malleolar area without nerve stimulator (NS) guidance. The PTN can also be blocked proximally (7 cm) above the medial malleolus in the subfascial plane between the flexor hallucis longus and flexor digitorum longus tendons. In this study we compared the frequency of successful PTN block at the traditional distal (D) site (2 cm above the medial malleolus) with and without NS guidance. We also compared block success and latency at the D site versus the proximal (P) block site.

METHODS

Subjects were randomized to P-NS (n = 45), D-NS (n = 45), or D without NS (n = 45). Levobupivacaine 0.625%, 0.15 mL/kg was used for all blocks. Pinprick sensory anesthesia was evaluated in the distribution of the medial plantar, lateral plantar, and medial calcaneal nerves. PTN block was considered successful if surgical anesthesia was achieved in all PTN distributions.

RESULTS

The frequency of successful PTN block was greater for D-NS (100%) and P-NS (93.5%), compared with D (73.3%) (P = 0.02). Median latency to complete block was less for D-NS (8 min, 95% CI 7-9 min) than D (20 min, 95% CI 13-26 min) (P < 0.01) and P-NS (15 min, 95% CI 12-18 min) (P = 0.04).

CONCLUSIONS

NS-guided needle placement improves the success and decreases the latency to onset of complete PTN block at the D site. The P approach to PTN block may be a useful alternative to the traditional D site approach, particularly in patients with restricted access to the D site.

Neurologic Sequelae After Interscalene Brachial Plexus Block for Shoulder/Upper Arm Surgery: The Association of Patient, Anesthetic, and Surgical Factors to the Incidence and Clinical Course

We determined the incidence, distribution, and resolution of neurologic sequelae and the association with anesthetic, surgical, and patient factors after single-injection interscalene block (ISB) using levobupivacaine 0.625% with epinephrine 1:200,000 in subjects undergoing shoulder or upper arm surgery, or both, in 693 consecutive adult patients. After a standardized ISB, assessments were made at 24 and 48 h and at 2 and 4 wk for anesthesia, hypesthesia, paresthesias, pain/dysesthesias, and motor weakness. Symptomatic patients were monitored until resolution. Subjects reporting pain or discomfort >3 of 10 and those with motor or extending sensory symptoms received diagnostic assessment. Six-hundred-sixty subjects completed 4 wk of follow-up. Fifty-eight neurologic sequelae were reported by 56 subjects. Symptoms were sensory except for two cases of motor weakness (lesions identified distant from the ISB site). Thirty-one sequelae with likely ISB association were reported by 29 subjects, including 14 at the ISB site, 9 at the distal phalanx of thumb/index finger, 7 involving the posterior auricular nerve, and 1 clinical brachial plexopathy. Sequelae not likely associated with the ISB were reported by 27 subjects with symptoms reported in the median (n = 9) and ulnar (n = 4) nerves, surgical neuropraxias (n = 12), and motor weakness (n = 2). Symptoms resolved spontaneously (median 4 wk; range, 2-16 wk) except in the two patients with motor weaknesses and the patient with clinical brachial plexopathy, who received therapeutic interventions. Variables identified as independent predictors of neurologic sequelae likely related to ISB were paresthesia at needle insertion and ISB site pain or bruising at 24 h. In contrast, surgery preformed in the sitting position, as well as ISB site bruising, was identified as a predictor of neurologic sequelae not likely related to ISB. In conclusion, neurologic sequelae after single-injection ISB using epinephrine mainly involve transient minor sensory symptoms.

Nerve Stimulator-Assisted Evoked Motor Response Predicts the Latency and Success of a Single-Injection Sciatic Block

Variable onset latency of single-injection sciatic nerve block (SNB) may result from drug deposition insufficiently close to all components of the nerve. We hypothesized that this variability is caused by the needle tip position relative to neural components, which is objectified by the type of evoked motor response (EMR) elicited before local anesthetic injection. One-hundred ASA I-II patients undergoing reconstructive ankle surgery received infragluteal-parabiceps SNB using 0.4 mL/kg (maximum 35 mL) of levobupivacaine 0.625%. The end-point for injection was the first elicited EMR: inversion (I), plantar flexion (PF), dorsiflexion (DF), or eversion (E) at 0.2-0.4 mA. The frequencies of the EMRs were: I 40%, PF 43%, E 14%, and DF 3%. SNB was considered complete if both tibial and common peroneal nerves were blocked and failed if either analgesia to pinprick was not observed at 30 min or anesthesia at 60 min. Patients with an EMR of I demonstrated shorter mean times (+/-95% confidence interval [CI]) to complete the block with 8.5 (95% CI, 6.2-10.8) min compared to 27.0 (95% CI, 20.6-33.4) min after PF (P < 0.001) and 30.4 (95% CI, 24.9-35.8) min after E (P < 0.001). No rescue blocks were required in group I compared with 24% (P = 0.001) and 71% (P < 0.001) of patients in groups PF and E, respectively. We conclude that EMR type during nerve stimulator-assisted single-injection SNB predicts latency and success of complete SNB because the observed EMR is related to the positioning of the needle tip relative to the tibial and common peroneal nerves.

[Minimally invasive, safe treatment of the neurogenic bladder with botulinum-A-toxin in children with myelomeningocele]

PURPOSE

The efficacy and durability of botulinum-A toxin in the treatment of detrusor hyperreflexia in myelomeningocele (MMC) children was evaluated prospectively.

MATERIALS AND METHODS

A total of 15 children (10 male and 5 female, mean age 5.8 years), all on clean intermittent catheterisation (CIC) due to MMC, were "non responders" to orally and intravesically administered anticholinergic medication. Pretreatment assessment included a videourodynamic evaluation, incontinence scoring and a mercaptoacetyltriglycine-3 renal scan. We injected from 10 U/kg up to a maximum of 360 U botulinum-A toxin at 25-40 sites of the detrusor, sparing the trigone. Follow-up was 24 months. All children had a urodynamic reevaluation with assessment of bladder capacity and incontinence score at 3, 9 and 12 months.

RESULTS

Mean bladder reflex volume increased from 72.00 +/- 28.12 ml to 298 +/- 32.45 ml (p < 0.001). The maximal detrusor pressure decreased from 78.76 +/- 23.14 cm H(2)O to 42.76 +/- 24.34 cm H(2)O (p < 0.001). Maximal bladder capacity increased from 136.34 +/- 45.71 ml to 297.02 +/- 87.17 ml (p < 0.001). Detrusor compliance increased from 18.29 +/- 27.19 ml/cm H(2)O to 51.17 +/- 38.17 ml/mmH(2)O (p < 0.001). While 10 patients became completely dry between CIC, the remaining 2 patients improved from score 3 to 1. Results at 9 months were similar to the ones at 3 months. The mean efficacy and durability of the toxin was 10.5 months after the first intravesical injection.

CONCLUSIONS

Botulinum-A toxin is a safe alternative in the management of detrusor hyperreflexia in MMC children. Preliminary results are promising concerning urodynamic parameters and continence.

Mineralized microstructure of calcified avian tendons: a scanning small angle X-ray scattering study

The micrometer level spatial distribution of the size, shape, and orientation of mineral crystallites in the calcifying matrix of tendons near the edge of the mineralizing front was investigated by scanning small angle X-ray scattering using synchrotron X-ray radiation. Using a special microbeam arrangement enabling 20 microm beam resolution and short measurement times, linear diffraction scans were made on sections from the normally calcifying tendons (tibialis cranialis) from the domestic turkey, which calcify in the distal to proximal direction. A change in shape and arrangement of mineral crystals was observed within the first 200 microm of the mineralization front, and the mineral crystal distribution was highly anisotropic with crystals aligned parallel to the fiber axis. In a cross-section of the tendon cut at right angles to the fiber axis, the orientation distribution of crystals was not azimuthally symmetric, and showed a small but nonzero anisotropy and a continuous change in mean orientation angle across the width of the tendon cross-section.

2 Years' experience with inspiratory muscle training in patients with neuromuscular disorders

PURPOSE

The aim of our study was to assess the long-term effects of specific inspiratory muscle training (IMT) in patients with neuromuscular disorders (NMDs) who have various degrees of respiratory impairment.

PATIENTS AND METHODS

Twenty-seven patients with NMDs (Duchenne's muscular dystrophy, 18 patients; spinal muscular atrophy, 9 patients) underwent 24 months of IMT. Patients were divided into three groups according to their vital capacity (VC) values. VC was measured as the parameter for the respiratory system involvement of the disease. Maximal inspiratory pressure (PImax) was assessed as the parameter for respiratory muscle strength, and the results of the 12-s maximum voluntary ventilation test (12sMVV) were assessed as the parameter for respiratory muscle endurance. Pulmonary and inspiratory muscle function parameters were assessed 6 months before training, at the beginning of training, and then every 3 months.

RESULTS

The PImax values improved in group A (VC, 27 to 50% predicted) from 51.45 to 87.00 cm H(2)O, in group B (VC, 51 to 70% predicted) from 59.38 to 94.4 cm H(2)O, and in group C (VC, 71 to 96% predicted) from 71.25 to 99.00 cm H(2)O. The 12sMVV values improved in group A from 52.69 to 69.50 L/min, in group B from 53.18 to 62.40 L/min, and in group C from 59.48 to 70.5 L/min. For all three groups, there was a significant improvement of PImax (p < 0.007) and 12sMVV (p < 0.015) until the 10th month when a plateau phase was reached with no decline in the following month until the end of training.

CONCLUSION

With IMT, respiratory muscle function can be improved in the long term of up to 2 years.

Dose-dependent effects of inspiratory muscle training in neuromuscular disorders

The goal of this study was to show whether a correlation exists between the intensity of specific respiratory muscle training and the improvement of strength and endurance in inspiratory musculature in patients with neuromuscular disorders (NMD). Sixteen patients with NMD (13 with Duchenne muscular dystrophy and 3 with spinal muscular atrophy) performed inspiratory muscle training (IMT) at home with a special training apparatus for 9 months. Maximal inspiratory mouth pressure (PI(MAX)) and 12s-maximum voluntary ventilation (12s-MVV) test served as parameters for inspiratory muscle strength and endurance, respectively. In patients whose inspiratory vital capacity (VC(in)) declined by less than 10% during the year before training began (n = 10), a significant positive correlation was found between the number of successfully completed strength and endurance exercises and the improvement of PI(MAX) (P < 0.05) and 12s-MVV (P < 0.05). In patients whose VC(in)-decline exceeded 10% (n = 6), indicating more progressive respiratory system involvement of the disease, no significant correlation between the improvement of PI(MAX) and 12s-MVV and the intensity of training was found. In patients with NMD, the effects of IMT-runs are dose-dependent, provided that the respiratory system involvement of the disease is only slowly progressive.

[Osteoporosis and metabolic bone diseases; clinical relationship]

Metabolic bone diseases with disturbed bone remodeling lead to loss of biomechanical quality and atraumatic fractures. Differential diagnosis, prevention and adequate treatment should already start early in the course of these disorders to prevent fractures. Thus, clinical osteology is more than the simplified connection "low bone mineral density--fractures--osteoporosis". This review summarizes physiological relations between bone tissue and calcium homoeostasis as well as the relation between structure and function. In addition, the main metabolic osteopathies "osteoporosis, primary hyperparathyroidism and osteomalacia" are presented from a clinical point of view. The importance and the diagnostic values of biochemical parameters and of the transiliacal biopsy are discussed. In this respect the quantitative measurement of the mineralization density (bone mineral density distribution = BMDD) seems to be of high value and extends the well established bone histomorphometry. This recently introduced method has the power to distinguish between small differences in the degree of mineralization of the matrix with high precision and reproducibility. The results of quantitative backscattered electron imaging in the scanning electron microscope improve the differential diagnosis of bone diseases with alterations in mineralization density, helps to detect mixed etiology (e.g. osteoporosis plus osteomalacia) and facilitate decision making for treatments. The value of biochemical, radiological, osteodensitometric and histopathological tests for diagnosis and treatment depends on the knowledge of the clinical relations and the complex interactions between calcium-, phosphate- and bone metabolism.