Hiroki Yajima

Surgical Treatment for Chronic Radial Head Dislocation

Background : The treatment of chronic radial head dislocation remains controversial. High rates of redislocation and complications have been reported after surgery. In our view, correction of malalignment with ulnar osteotomy is the key to a good surgical result. Methods: Since 1975, twenty-two patients were treated surgically for chronic radial head dislocation at our hospital. The procedure consisted of open reduction of a dislocated radial head followed by radial and/or ulnar osteotomy, with or without reconstruction of the annular ligament or by reconstruction of the annular ligament alone. The ages of the patients ranged from four to twenty years. In 1991, we modified the surgical technique by performing an oblique ulnar osteotomy with angulation and elongation and rigid plate fixation. Bone-grafting at the osteotomy site was also performed if necessary. A cast was applied with the forearm in neutral rotation and was worn for two to four weeks. Nine patients were treated with this modified technique. Results: The mean interval between the initial injury and the reconstructive surgery was ten months. There were no serious surgical complications. Of the thirteen patients treated before 1991, four had a good reduction and seven had redislocation. Seven patients had restricted forearm rotation postoperatively. Of the nine patients treated with the modified osteotomy since 1991, seven had a good reduction. Two patients, who had had slight radial head deformity preoperatively, had subluxation postoperatively. Two patients had restricted forearm rotation. Conclusions: Since we modified our technique for ulnar osteotomy, good reduction of the radial head has been achieved without causing serious contracture. Both angulation and elongation of the ulna are required to allow the radial head to reduce.

Surgical outcome of radial osteotomy for Kienböck's disease : minimum 10 years of follow-up

PURPOSE Long-term results of radial osteotomy for Kienböcks disease seldom are seen in the literature. The purpose of this study was to report the minimum 10-year results and to compare them with the 5-year results to determine whether the favorable intermediate-term results were maintained. METHODS Twenty-five patients who underwent radial osteotomy were followed-up for a mean period of 14.5 years. They were examined for pain, grip strength, and wrist range of motion (ROM). Through a review of clinical records, 5-year postoperative results were collected. The carpal height ratio and Ståhls index were measured and the x-rays were inspected for osteoarthritic changes. We devised an original lunate grade to evaluate radiologic improvement of the ischemic lunate. Overall results were evaluated using Cooneys wrist function score and Nakamuras scoring system for Kienböcks disease. The long-term results were compared with both the preoperative status and the 5-year results. RESULTS Pain, ROM, and grip strength were improved significantly after surgery, and the results were maintained for a long period. Carpal height ratio and Ståhls index did not show significant improvements but ischemic lunate showed certain radiologic improvements with time by the lunate grade system. Osteoarthritic changes were observed in 54% of patients at 5 years and in 73% of patients at the final follow-up evaluation, but the arthrosis generally was mild and did not affect the clinical results. Cooneys wrist function score was excellent or good in 96% of the patients, and the results with Nakamuras scoring system for Kienböcks disease were excellent or good in 68% of the patients at the final follow-up evaluation. The percentages were the same 5 years after surgery. CONCLUSIONS Radial osteotomy for Kienböcks disease is a reasonable treatment option and clinical improvement lasts for a long period of time. Although radiologic improvement was not drastic, the inner structure such as sclerotic change or bone cysts of the lunate improved with time, indicating healing of the ischemic lunate. Severe osteoarthritic change or proximal migration of the capitate can be avoided.

The immunosuppressant FK506 activates capsaicin- and bradykinin-sensitive DRG neurons and cutaneous C-fibers

Immunosuppressant drug FK506, which is widely used for the treatment of atopic dermatitis, has multiple actions on the nervous system. In order to elucidate the mechanisms underlying transient burning sensation elicited by topical application of FK506 to the skin of atopic patients, we investigated if FK506 directly activates sensory neurons and fibers, or not. Ca(2+) imaging study on cultured DRG neurons of rats revealed that application of FK506 raised intracellular Ca(2+) levels in a subpopulation of small DRG neurons (3.1% of DRG neurons responsive to high K(+) solution). When DRGs from inflamed rats were used, the incidence increased to 7.4%. FK506 sensitive neurons also responded to a subsequent application of capsaicin (89.5% in normal, and 100% in inflamed rats) and bradykinin (31.6% in normal, and 80.9% in inflamed rats). Single fiber recordings in the skin-nerve preparation confirmed the results of cell culture study, showing that application of FK506 enhanced neuronal discharges of single C-fibers that are responsive to heat and bradykinin. These findings, taken together, indicate that FK506 application on inflamed skin may activate nociceptive C-fibers, which bear bradykinin receptors and capsaicin-sensitive heat transducer of TRP family, TRPV1.

Differences between the Lewis and Sprague-Dawley rats in chronic inflammation induced norepinephrine sensitivity of cutaneous C-fiber nociceptors

We investigated whether there are any differences between the Lewis and Sprague-Dawley (SD) rats in chronic inflammation-induced norepinephrine (NE) sensitivity of nociceptors. Activities of C-fiber nociceptors innervating rat hairy hindpaw skin were recorded in an in vitro skin-nerve preparation. Sixty-five percent of C-fibers from inflamed Lewis rats were excited by NE (10 microM), against only 38% of C-fibers from inflamed SD rats. The average of the total impulses evoked in response to NE was also significantly higher in Lewis rats. The alpha2-adrenoceptor antagonist CH 38083 (10 microM) and yohimbine (10 microM) consistently blocked the NE-excitation of both strains. These results show that after chronic inflammation, C-fiber nociceptors of Lewis strain rats have a stronger sensitivity to NE, and that alpha2-adrenoceptors are predominately involved in the NE-sensitivity of inflamed rats in both strains.

Distraction Lengthening of the Forearm for Congenital and Developmental Problems

Thirty-five callus distractions of the forearm were carried out in 23 patients, who were divided into two groups according to the cause of the shortening. Eleven cases in group A had congenital dysplasia, and the 12 cases in group B had growth disturbances from tumours or infection. The mean amount of lengthening was 27 mm in group A and 25 mm in group B. The mean percentage increase in length was 35% and 17%, respectively. The mean duration of fixation was 159 days and 127 days, respectively. The Healing Index had a positive correlation with the age at surgery in group A, but not in group B. The main complication was callus deformity after the removal of a fixator, which was especially frequent in group A. To avoid complications, the aetiology of shortening and the age of the patient should be considered when deciding the surgical protocol.

Inhibitory, facilitatory, and excitatory effects of ATP and purinergic receptor agonists on the activity of rat cutaneous nociceptors in vitro

Pathological pain is often associated with changed sympathetic nerve activities. It is known that sympathetic nerve endings release ATP as a co-transmitter of norepinephrine, but the effect of this ATP on the nociceptive system has not been properly studied in that the concentration range used in the previous studies was much higher than is expected in the surroundings of nociceptor terminals. We examined the effects of ATP, especially at low concentration (10(-5) M or less), on C-fiber polymodal receptor (CPR) activity using a rat skin-nerve preparation in vitro. We found for the first time that ATP inhibited the heat response of CPRs at low concentration (10(-5) M), but facilitated it at high concentration (10(-3) M). The former effect was mimicked by a P2X3 agonist, alpha,beta-methylene ATP, at 10(-5) M, while the latter was mimicked by 2-methylthio ADP (a P2Y1 agonist) or UTP (a P2Y2 agonist) at 10(-3) M, suggesting that the former is mediated by P2X receptors and the latter by P2Y receptors. After repetitive heat stimuli, ATP-induced CPR excitation was increased (10(-5) to 10(-3) M), but none of the purinergic agonists induced CPR excitation in a magnitude comparable to that by ATP. Possible mechanisms for these effects were discussed.

Interactions of bradykinin and norepinephrine on rat cutaneous nociceptors in both normal and inflamed conditions in vitro

Many inflammatory chemical mediators excite or sensitize nociceptors, which had led some researchers to believe that they may interact with each other to maintain a persistent painful state. We examined how the excitatory mediators norepinephrine (NE) and bradykinin (BK) interact, using single fiber recordings from cutaneous nociceptors. We observed that NE augmented the BK-induced response in both control and adjuvant-inflamed rats in a way different from NE-induced excitation in inflamed animals only. BK also tended to augment the NE-induced response (examined only in inflamed rats). Our results provide the first evidence that BK and NE synergistically interact on nociceptors.

Loose Body in the Wrist: Diagnosis and Treatment

PURPOSE The purpose of this study was to report on 10 cases of symptomatic loose bodies in the wrist joints diagnosed using arthroscopy. TYPE OF STUDY Retrospective review. METHODS From 1986 to 2000, we performed wrist arthroscopy for 707 patients, 10 of whom had loose bodies in the wrist joints. The clinical records were reviewed retrospectively. The patients included 8 men and 2 women, and the average age was 28 years (range, 16 to 67 years). The chief complaint was wrist pain in all patients, but locking was uncommon. Preoperative diagnosis was difficult in all but 3 cases; in those cases, an osseous component was found within the loose bodies. The remaining cases were diagnosed by wrist arthroscopy. RESULTS The loose bodies existed in the radiocarpal joint in 5 cases, and all could be removed arthroscopically. In the other 5 cases, the loose bodies were in the distal radioulnar joint, and arthrotomy was needed to remove them. After removal of the loose bodies, the pain was relieved in all cases without any surgical complications. CONCLUSIONS Loose bodies in the wrist joint should be included in the differential diagnosis for chronic wrist pain. Wrist arthroscopy is of value because the preoperative diagnosis is usually difficult.

Norepinephrine reduces heat responses of cutaneous C-fiber nociceptors in Sprague–Dawley rats in vitro

Nociceptors are excited or sensitized by many inflammatory mediators as well as by elevation of tissue temperature. We have shown that there is a facilitatory synergistic interaction between norepinephrine (NE) and bradykinin (BK) on cutaneous C-fiber nociceptors in normal Lewis rats. These interactions may play an important role in the mechanism of sympathetically maintained pain. In the present experiment, using skin-saphenous nerve in vitro preparations, we tested the effect of NE on the activity of nociceptive fibers and their response to heat in normal Sprague-Dawley rats. For comparison with the previous data on Lewis rats, we also examined the effect of NE on BK response. NE (10(-5) or 10(-6) M) did not excite nociceptive fibers before repeated heat stimuli or BK superfusion (10(-5) or 10(-6) M) to the receptive field. In contrast, after a few applications of heat or BK, NE excited 20-43% of nociceptive fibers to similar magnitudes. We also found that NE sensitized subsequent BK responses, but somewhat unexpectedly that it suppressed subsequent heat responses. This occurred regardless of the presence or absence of NE-induced excitation. These results suggest different mechanisms of NE modification to the BK and heat responses of cutaneous C-fiber nociceptors.