Tomokazu Fukui

Frequency-dependent ERK phosphorylation in spinal neurons by electric stimulation of the sciatic nerve and the role in electrophysiological activity

The phosphorylation of extracellular signal-regulated kinase (pERK) in DRG and dorsal horn neurons is induced by the C-fiber electrical stimulation to the peripheral nerve. The present study was designed to investigate the expression and modulation of pERK in the rat dorsal horn neurons produced by repetitive electrical stimulation, and its involvement in the electrophysiological activity of dorsal horn neurons. Electrical stimulation of C-fiber intensity at different frequencies was applied to the sciatic nerve; the stimuli-induced pERK expression and the activity in dorsal horn neurons were studied by immunohistochemistry and extracellular recording, respectively. Electrical stimulation of C-fibers (3 mA) induced pERK expression in dorsal horn neurons in a frequency-dependent manner, indicating that the frequency of electrical stimulation is an important factor which activates the intracellular signal pathway in the spinal cord. To demonstrate the underlying mechanism of this frequency-dependent pERK expression, an NMDA receptor antagonist, MK-801, and a voltage sensitive calcium channel antagonist, nifedipine, were administrated intrathecally before the stimulation. We found that high frequency (0.5 Hz and 10 Hz) but not low frequent (0.05 Hz) stimulus-evoked pERK was partially inhibited by MK-801. Both high and low frequency stimulus-evoked pERK were inhibited by the nifedipine treatment. The extracellular single unit activities were recorded from the laminae I-II and V of the L4-5 dorsal horn, and we found that blockage of the intracellular ERK signal suppressed the wind-up responses in a dose-dependent manner. In contrast, any change in the mechanically evoked responses was not observed following the administration of ERK inhibitor. These observations indicate that ERK activation plays an important role in the induction of the wind-up responses in dorsal horn nociceptive neurons.

Results of total hip arthroplasty for dialysis arthropathy in long-term hemodialysis patients

BackgroundThe number of hemodialysis patients has progressively increased in Japan. Among the orthopedic complications in this population, chronic hip arthropathy associated with long-term hemodialysis is one of the most devastating problems. Total hip arthroplasty (THA) is often indicated. However, varying results have been reported for THA in these patients. This study was undertaken to assess the risk-benefit ratio of THA performed in patients with dialysis hip arthropathy.MethodsWe evaluated 17 patients (19 hips) with dialysis hip arthropathy who underwent THA. The duration of hemodialysis before surgery ranged from 10 to 27 years. Histological examination of the tissue samples revealed accumulation of amyloid deposits in all cases. Three patients died within 2 years after operation; the remaining 14 patients (16 hips) were followed for a minimum of 3 years.ResultsThe cumulative survival rate of the prostheses in these 16 hips up to the latest follow-up was 94%. Regarding surgery-related complications, deep infection occurred in one hip, and revision THA was required in one patient with recurrent dislocation and aseptic loosening.ConclusionsTHA for dialysis hip arthropathy in long-term hemodialysis patients is associated with substantial local and general risks. Despite the substantial risk, THA for this patient population seems to afford reasonably satisfactory results.

Combined anteversion of the total hip arthroplasty implanted with image-free cup navigation and without stem navigation

In total hip arthroplasty (THA), combined anteversion (CA), the sum of cup anteversion (AV) and stem antetorsion (AT) are used as parameters to assess the appropriateness of overall prosthetic alignment. In this study, we evaluated the CA value based on the post-operative computed tomography (CT) measurements in our patient population who underwent THA using the OrthoPilot™ image-free navigation system (B/BRAUN-Aesculap, Tuttlingen, Germany). During surgery, cup alignment was adjusted with the use of the navigation system while the positioning of the femoral stem was arbitrarily adjusted by the surgeon. Seventy-nine THAs were included in the study. Post-operative CT assessment for the prosthetic alignment showed the average cup inclination and AV values to be 40.5°±4.1° and 20.6°±4.6°, respectively, demonstrating the effectiveness of the navigation system by small values of standard deviation. By contrast, the AT value measured for the stem showed wide variability (mean 23.6°±11.2°). Consequently, the resulting CA was also inconsistent (mean 44.4°±11.2°) and only 61 of the 79 THAs (77.2%) were defined as satisfactory.

Use of Image-Free Navigation in Determination of Acetabular Cup Orientation: Analysis of Factors Affecting Precision

We have been using an image-free total hip arthroplasty (THA) navigation system (OrthoPilot; Aesculap, Tuttlingen, Germany) to ensure accurate and reproducible acetabular cup orientation. In this study, the accuracy of this system in the assessment of acetabular cup orientation was evaluated by comparing the intraoperative inclination and anteversion angles presented by the navigation system and the corresponding postoperative values obtained by computed tomography measurement. In the intraoperative accuracy analysis, we additionally examined the influence of factors such as body mass index and soft tissue thickness on assessment error. Intraoperative and postoperative results obtained from 115 consecutive navigated THAs were compared and analyzed. In both inclination and anteversion angles, good agreement was observed; a discrepancy of more than 5° was observed in 1 and 3 cases, respectively. In the analysis of factors potentially affecting the accuracy of the intraoperative assessment, no correlation between each parameter and the intraoperative and postoperative discrepancy was demonstrated.

Multiple pelvic insufficiency fractures in rheumatoid patients with mutilating changes

Multiple insufficiency fractures occurred in two patients with mutilating rheumatoid arthritis (RA), leading to substantial disabilities. Both patients received long-term oral glucocorticoid therapy and underwent multiple lower-extremity surgeries such as total hip arthroplasty (THA) or Total knee arthroplasty (TKA). The multiple fractures were located in the pelvis and lumbosacral region. Fractures in both patients were treated conservatively. Although bony union and resumption of activities were achieved in one patient, the other patient was not able to resume ambulation. For RA patients with combined risk factors for insufficiency fractures, aggressive preventive intervention and careful clinical assessment for early detection and management are warranted.

Comparison of Continuous Femoral Nerve Block, Caudal Epidural Block, and Intravenous Patient-controlled Analgesia in Pain Control After Total Hip Arthroplasty: A Prospective Randomized Study

Thirty-six patients who underwent primary unilateral total hip arthroplasty (THA) were randomly allocated to 4 groups with different pain control protocols; continuous femoral nerve block (FNB group), single-shot caudal epidural block with morphine (EB group), intravenous patient-controlled analgesia with fentanyl (IV-PCA group), and systemic administration of nonsteroidal anti-inflammatory drugs (NSAIDs group). Postoperative pain was assessed using the numerical rating scale (NRS) scores and the analgesic effect was compared among the groups. The NRS upon arrival at the recovery room and 6 hours after surgery in the FNB, EB, and IV-PCA groups were significantly lower than that in the NSAIDs group. The amount of additional analgesics requested by the patient was smaller in the FNB, EB, and IV-PCA groups as compared to the NSAIDs group. Regarding the complications related to the analgesia, 5 of the 9 patients in the IV-PCA group complained nausea and vomiting and received antiemetic drugs. Delay in the rehabilitation process due to drowsiness was encountered in 3 patients in this group, while no patient in the FNB and EB groups suffered from delayed rehabilitation. Considering both the analgesic effect and the potential risk of complications, continuous femoral nerve blocks and caudal epidural blocks for are recommended for postoperative pain control after THA procedure.

Assessment of acetabulum anteversion aligned with the transverse acetabulum ligament: cadaveric study using image-free navigation system

The transverse acetabulum ligament (TAL) has been used as an intraoperative anatomical landmark to position the acetabulum cup in total hip arthroplasty (THA). However, the validity of the use of TAL has not been clarified. The purpose of this study was to examine the orientation of the cup component aligned with the TAL in cadaveric study. The 31 hips in 25 whole-body embalmed cadavers were examined. The donors were 12 men and 13 women. Simulated THA procedure using image-free navigation system was performed and a trial cup with a diameter of approximately 2 mm less than the size of the acetabulum were inserted and snugly fitted on the TAL through the posterior wall of acetabulum. The orientation of the cup component was measured using an image-free THA navigation system. The measured radiographic anteversion and inclination angles averaged 18.2±7.2° (range: 2.0–33.2°) and 43.5±4.2° (range: 33.1–51.0°) respectively. Based on the Lewinneks safe zone criteria, 26 hips (80.6%) were judged to be within the. Moreover, in the analysis of the gender difference of TAL angles, the average anteversion angle was shown to be significant larger in female than male population. The TAL can be effectively used an intraoperative landmark to align the acetabulum component helping reduce the risk of dislocation after surgery. In the intraoperative judgment, a gender difference in the alignment of the TAL should be taken into consideration.

Radiological classification of hip arthropathy associated with long-term haemodialysis.

Various types of hip lesion associated with long-term haemodialysis have been observed. We present a new radiological classification system of haemodialysis-related hip arthropathy. In total, 103 hip lesions were analyzed in 84 patients undergoing haemodialysis for more than ten years. The hip lesions were classified into 3 types; Type I - cystic type with further subdivisions based on cyst location, Type II - arthritic type, and Type III - deformity of the femoral head. Surgery was performed on 60 hips. We believe our classification system assists decision making on behalf of these patients.

Femoral artery injury during revision of a dislocated bipolar hemiarthroplasty: a case report.

Although rarely encountered, major vascular injury is a serious complication of total hip arthroplasty (THA). We report the case of an 85-year-old woman who sustained a deep femoral artery injury associated with a superficial femoral artery thrombosis during revision of a dislocated bipolar hemiarthroplasty to a THA. Altered anatomy due to migration of the femoral head was thought to be one of the factors leading to this complication. Following the revision procedure, no signs of vascular insufficiency were detected in the immediate postoperative period, but ischaemia was clinically evident 12 hours after surgery. The importance of careful preoperative and postoperative assessment is addressed.

Comparison of continuous femoral nerve block with and without combined sciatic nerve block after total hip arthroplasty: a prospective randomized study

In association with the growing interests in pain management, several modalities to control postoperative pain have been proposed and examined for the efficacy in the recent studies. Various modes of peripheral nerve block have been proposed and the effectiveness and safety have been examined for each of those techniques. We have described our clinical experiences, showing that continuous femoral nerve block could provide a satisfactory analgesic effect after total hip arthroplasty (THA) procedure. In this study, we compared the effectiveness and safety of continuous femoral nerve block with and without sciatic nerve blockade on pain control after THA. Forty patients scheduled for THA were included in the study and randomly divided into 2 groups. Postoperative analgesic measure was continuous femoral nerve block alone, while the identical regimen of continuous femoral nerve block was combined with sciatic nerve block. The amount of postoperative pain was evaluated in the immediate postoperative period, 6 hours, and 12 hours after surgery. Moreover, postoperative complications as well as requirement of supplemental analgesics during the initial 12 hours after surgery were reviewed in the patient record. The obtained study results showed that the supplemental sciatic nerve blockade provided no significant effect on arrival at the postoperative recovery room, while the NRS pain score was significantly reduced by the combined application of sciatic nerve blockade at 6 and 12 hours after surgery. In the investigation of postoperative analgesiarelated complications, no major complication was encountered without significant difference in complication rate between the groups.