A novel ultrahigh-resolution surface plasmon resonance biosensor with an Au nanocluster-embedded dielectric film.

The detection performance of conventional surface plasmon resonance (SPR) biosensors is limited to a 1 pg/mm(2) surface coverage of biomolecules, and consequently, such sensors struggle to detect the interaction of small molecules in low concentrations. The present study is attempted to propose the use of a novel SPR biosensor with Au nanoclusters embedded in a dielectric film to achieve a 10-fold improvement in the resolution performance. A co-sputtering method utilizing a multi-target sputtering system is used to fabricate the present dielectric films (SiO(2)) with embedded Au nanoclusters. It is shown that the sensitivity of the developed SPR biosensor can be improved by adjusting the size and volume fraction of the embedded Au nanoclusters in order to control the surface plasmon effect. The present gas detection and DNA hybridization experimental results confirm that the proposed Au nanocluster-enhanced SPR biosensor provides the potential to achieve an ultrahigh-resolution detection performance of approximately 0.1 pg/mm(2) surface coverage of biomolecules.

Changes in conduction, blood flow, histology, and neurological status following acute nerve-stretch injury induced by femoral lengthening.

The effects of an acute stretch on evoked potential, blood flow, histological change, and clinical neurological state were studied in a rat model of acute nerve stretch induced by femoral lengthening. The purposes of this study were to assess, in a model of acute limb lengthening, the safe limits of nerve stretch for nerve function, the pathogenesis of nerve dysfunction, the sensitivity of spinal somatosensory evoked potential, and one of the proposed criteria for irreversible compromise of the sciatic nerve. Thirty-two rats were assigned to one of four groups defined by the degree of acute femoral lengthening (8, 16, 24, and 32%). Spinal somatosensory evoked potential at L5/6 following stimulation of the sciatic nerve was recorded before, immediately after, and 30 minutes after lengthening. Sciatic nerve blood flow was measured by laser Doppler flowmetry at the stretched site before and after lengthening. One week after the operation and without further lengthening, clinical neurological status was evaluated by the functional index of the sciatic nerve and histological examination was performed. At the measurement immediately after the procedure, amplitude changed significantly in all groups except for the group with 8% lengthening. In all groups, sciatic nerve blood flow also dropped significantly compared with values for the control side. Moreover, a greater percentage increase in acute lengthening corresponded with more marked changes in spinal somatosensory evoked potential and sciatic nerve blood flow. The groups that underwent acute lengthening of 24 and 32% had significant neurological deficits and histological changes and demonstrated a significant and profound (50%) drop in amplitude and blood flow. We concluded that spinal somatosensory evoked potential is very sensitive and may serve as an effective tool for the early detection of impending acute nerve-stretch injury and that a 50% reduction in amplitude indicates irreversible damage.

Gait analysis after total hip arthroplasty with leg-length equalization in women with unilateral congenital complete dislocation of the hip--comparison with untreated patients.

Patients with Crowe Type-IV congenital dislocation of the hip (CDH) show significant clinical improvement after total hip arthroplasty (THA) because this surgery greatly reduces pain. Concomitant leg-length equalization in unilateral patients--a controversial procedure--theoretically should significantly improve these patients' ability to walk efficiently and comfortably. To understand the impact of leg-length equalization on these patients, we compared their gait parameters with those of untreated patients without pain but with leg-length discrepancy. Using a motion analysis system, three force platforms and computer calculation, the gait parameters during level walking of 22 women with unilateral Crowe Type-IV CDH were studied at an average of 58 months (27-98 months) following a successful cementless THA. The socket was placed in the best bone stock, which was close to the level of the true acetabulum. The leg-length discrepancy was equalized to within 2 cm in all patients. The Harris hip score averaged 94.8 (range, 88-100) at the time of the study. Nine women with untreated unilateral Crowe Type-IV CDH without major pain but with an average leg-length discrepancy of 4.7 cm (range, 2.5-6 cm) were also studied for comparison. The treated subjects (Group 1; THA and leg-length equalization) walked faster and had gait parameters with better bilateral symmetry than the untreated subjects (Group 2). We concluded that leg-length equalization in addition to THA in patients with unilateral Crowe Type-IV CDH significantly improves gait symmetry and efficiency.

Arthrodesis with a short Huckstep nail as a salvage procedure for failed total knee arthroplasty.

Arthrodesis of the knee with use of a short Huckstep nail was performed in thirty-three patients (thirty-three knees) after failure of a non-constrained total knee arthroplasty. The indication for the arthrodesis was an infection in thirty-one knees and a Charcot joint in two. Three knees had had a failed attempt at arthrodesis with use of external fixation. The Huckstep nail was inserted through the knee, retrograde into the femur, and then antegrade into the tibia. The duration of the operation averaged 104 minutes (range, sixty-five to 155 minutes). Local bone graft was used in all knees. At the time of follow-up, at an average of forty-seven months (range, eighteen to ninety-four months), thirty knees (91 per cent) had radiographic evidence of union. The average time to union was 5.2 months (range, two to ten months) after the arthrodesis. Eight knees that had a grossly purulent infection were treated with debridement, which was followed by the arthrodesis as a second-stage procedure; the other knees had a one-stage arthrodesis. Only one of the thirty-one knees that had had an infection before the arthrodesis had a recurrence after it. Arthrodesis with a short Huckstep nail provides immediate axial and rotational stability and allows weight-bearing without use of external support as well as placement of the knee in a slightly flexed and valgus position. In addition, the nail does not migrate and it may be used even when there is a standard-size prosthesis in the ipsilateral hip.

Neuromonitoring of an experimental model of clip compression on the spinal nerve root to characterize acute nerve root injury.

OBJECTIVES: To evaluate the sensitivity of an electro-monitoring method in acute nerve root injury, and to determine a proposed criterion for irreversible electrophysiologic degradation. STUDY DESIGN: Acute nerve root injury was induced by a clip compression model in rabbits, mimicking nerve root injury by a transpedicular screw. A common neuromonitoring technique, spinal somatosensory-evoked potential, was used to study the electrophysiologic change during the procedure. SUMMARY OF BACKGROUND DATA: With the advent of the transpedicular screw system, increased risk of injury to the spinal root because of the passage of screws is not unexpected. Although both an experimental model and a clinical application in intraoperative neuromonitoring of spinal cord function have been established, the value of neuromonitoring of an acute spinal root injury remains obscure. Several neurophysiologic surveillance techniques have been used successfully to monitor the potential injury to the spinal cord during orthopedic procedures around the spinal cord and spinal column. Spinal somatosensory-evoked potential, which has the advantages of high amplitude and quick recording time, is used to detect nerve root impairment during the insertion of transpedicular screws. METHODS: Experimental acute nerve root injury was induced in rabbits by direct hemostatic clip compression on the nerve root (S1) during different time intervals. Spinal somatosensory-evoked potential elicited by stimulating the sciatic nerve and recorded from a needle electrode at the L6-L7 interspinous ligament was monitored immediately before and after compression. RESULTS: Spinal somatosensory-evoked potential is sensitive enough to detect the compromise of a single nerve root and that a decrease in the amplitude is the most reliable and sensitive sign. With this model, there was a statistically significant correlation between the compression time and reduction of amplitude and delay of latency. The criterion for irreversible electrophysiologic change was an amplitude loss of more than 20% and a delay in latency immediately after nerve root compression. CONCLUSIONS: It was concluded that spinal somatosensory-evoked potential can provide immediate feedback of nerve root injury and should be considered for use during the dynamic phase of transpedicular screw insertion.

The effect of changing the foot progression angle on the knee adduction moment in normal teenagers.

The effect of changing the foot progression angle on the peak knee adduction moment (KAM) during stance was investigated in 48 teenagers. They underwent gait analysis when walking in three different postures: normal walking, intentional in-toeing, and intentional out-toeing. The peak KAM when in-toeing was the highest and was statistically different from that seen in the normal walking or in the out-toeing posture. These findings may have clinical significance in adult life.

Application of locked intramedullary nails in the treatment of complications after distraction osteogenesis.

Distraction osteogenesis (callotasis) has been widely used in patients with limb-length inequality or massive bone defects. This procedure, however, may be associated with a high incidence of physical and psychosocial complications. Callotasis telescoping on a locked intramedullary nail has been used to shorten the period of external fixation. Little attention has been given to the use of locked intramedullary nails in the treatment of complications after callotasis. Between 1990 and 1999, we used locked intramedullary nailing in 27 patients for the treatment of complications after distraction osteogenesis. There were 17 men and ten women with a mean age of 33.2 years (16 to 66). The nail was inserted at a mean of 3.4 weeks (0 to 15) after removal of the external fixator. Simultaneous autogenous bone grafting and soft-tissue reconstruction were also undertaken in seven and two patients, respectively. There was consolidation of the callus or docking site in all patients at a mean of 6.4 months (2 to 14) after surgery. The mean shortening of the callus was 0.7 cm (0 to 2.5). Two patients had infection at the site of a distal screw which resolved after removal of the nail. In 17 patients the nail was removed at a mean of 26 months after its insertion. Locked intramedullary nails are useful in treating complications after distraction osteogenesis in skeletally mature patients. The risk of infection should be borne in mind.

Synchronous pyomyositis and septic hip arthritis.

The authors report a rare concomitant pyogenic infection of the iliopsoas, iliacus and external obturator muscles and of the hip joint in a 68-year-old woman. Because the patient showed the classic symptomatic triad of limping, hip pain and fever, in addition to positive hip arthrocentesis, the diagnosis of septic hip arthritis was routine, but the simultaneous pyomyositis was almost overlooked. Unusual localised heat and swelling on the front of the proximal thigh prompted a CT scan that identified remarkable muscle abscesses in addition to the septic arthritis. Surgical debridement and antibiotics resolved the infection relatively rapidly without sequelae. We noted that reaching a definitive diagnosis of such a concomitant infection requires a suspicion of the presence of pyomyositis, which can be definitively determined using advanced imaging studies.

Treatment of femoral shortness due to nonunion or malunion by distraction device and Huckstep instrumentation.

Eighteen adult patients with nonunion or malunion of the femur and leg length discrepancy were treated with Wagner's distraction device and Huckstep instrumentation in one or two-staged operations. The Huckstep nail is introduced into the medullary cavity. Screws are transfixed to one segment before distraction. After completion of distraction, screws are transfixed to the other segment. Autogenous bone graft or allograft is also transfixed to fill up the gap. Continuous passive motion of the knee is conducted between operations and after operation. Postoperative protection is not necessary. All 12 patients who were operated for more than nine months had united and are reported here. Both patients with previous infection of the bone had flare up of the infection which was controlled medically. Both healed and united finally. No patient had contracture of the knee. This method corrects deformity and prevents angulation during distraction. Postoperative care is simple. The patient can return to his work soon after he is discharged. This method is not recommended for infection, bone of small caliber and desired lengthening for more than 6 centimeters.

Changes in coagulatory profile after orthopedic surgery.

Platelet count, prothrombin time (PT), partial thromboplastin time (PTT) and fibrinogen concentrations were prospectively evaluated in 65 patients undergoing orthopedic surgery at the National Cheng-Kung University Hospital between June 1990 and February 1991. All patients were hospitalized for at least 7 days after surgery. Coagulation data were collected preoperatively and on the first, third and seventh postoperative days (POD 1, 3, 7). The average estimated blood loss was 374 mL (range, 25-2.350 mL). Stored whole blood transfusion of 2 to 5 units (1 unit = 250 mL) was required by 12 patients. A further 12 patients received a transfusion of two to six units of packed red cells. Platelet count decreased to the lowest level on POD 1, recovered to normal on POD 3 and was even greater by POD 7. PT was prolonged on POD 1, recovered by POD 3 and remained stable on POD 7. PTT was prolonged on POD 1, became more prolonged on POD 3 and returned to normal by POD 7. Fibrinogen concentrations were not significantly altered on POD 1, but increased above the preoperative level on POD 3 and returned gradually to normal by POD 7. Variables such as age, sex, type of operation and duration of tourniquet did not affect these patterns. There was a positive correlation between duration of surgery, net blood loss and decrease in platelet count. This study examined some of the physiologic coagulatory variations after orthopedic surgery. Recognition of these patterns might lead to better clinical judgment when perioperative coagulatory disorders are suspected.

Gait analysis of adult patients with complete congenital dislocation of the hip.

Comprehensive gait analysis is valuable in understanding the performance of patients with lower limb disorders. The gait pattern of adult patients with untreated congenital dislocation of the hip (CDH) has not yet been reported. We studied the gait pattern in nine women (mean age 31.4 years) with Crows group IV CDH. Six had unilateral and three had bilateral involvement. They were not treated during childhood and had no pain at the time of study. A control group comprised 15 normal female subjects of the same age group. Gait was studied using a motion-analysis system, force plateforms, and computer calculation during level walking. Common abnormal gait patterns seen in patients with both unilateral and bilateral CDH were slower walking velocity, which was due to a shorter stride length, less forward tilting of the pelvis, insufficient flexion, and excessive internal rotation of the hips. The patients with unilateral CDH had a shorter step length, lower pelvis, a lateral shift of the ground reaction force, decreased maximum adduction moments of the hip and knee on the diseased side, and increased maximum adduction moments of the hip and knee on the unaffected side. This asymmetry may have been due to leg length inequality. Thus, correlation of the leg length discrepancy may be important for unilateral CDH patients in improving their gait.

Cementless reimplantation of hydroxyapatite-coated total hips after periprosthetic infections.

From February 1991 to July 1993, 26 hydroxyapatite (HA) coated total hips were implanted in 26 patients with infected hip prostheses. Seven were done as one-stage exchange arthroplasties and the other 19 were delayed reimplantations. Successful reimplantation was defined as a functioning hip without recurrence of infection at least 2 years after reimplantation. During a follow-up period of 25 to 54 months, 24 of the reimplantations were successful. Our success rate using the HA-coated prosthesis is similar to previous reports that used antibiotic impregnated bone cement. The HA method avoids the complications encountered with bone cement.

Acute median nerve injury due to migration of a Kirschner wire.

Migration of orthopaedic implants such as K-wires is not unusual, but migration due to an improperly constructed brace has not been reported. This report describes such a mechanism in a case complicated by acute median nerve injury.

Pyomyositis--with special reference to the comparison between extra- and intrapelvic muscle abscess.

Fifteen patients, nine males and six females, diagnosed with pyomyositis from 1988 to 1994, and followed for an average of 69.8 months, were reviewed. Excluding two children, the average age was 56.6 years. Eleven adults (73.3%) had underlying diseases. The lesions were multiple in five patients (33.3%) and a total of twenty-four muscle abscesses, including eleven extrapelvic and thirteen intrapelvic, were identified. When comparing extra- and intrapelvic pyomyositis, intrapelvic pyomyositis presents a diagnostic challenge requiring a high index of suspicion. Distinct clinical features such as local heat and painful swelling were all identified in extrapelvic pyomyositis, but they rarely (in only two of the thirteen lesions) emerged in intrapelvic pyomyositis. The average time from presentation to diagnosis was significantly longer in intrapelvic than in extrapelvic pyomyositis (1.4 vs 9.7 days). Although aspiration showed a high diagnostic rate in extrapelvic muscle abscesses, it was difficult to perform and was occasionally misinterpreted in intrapelvic cases. Routine X-rays were not helpful in making the diagnosis. CT scan was valuable because it provided positive diagnostic findings in all twelve patients who received one. The causative organisms in our patients were Staphylococcus aureus in eight (53.3%), Escherichia coli in three (20%), and Klebsiella in three (20%). Treatments consisted of parenteral antibiotics for all patients, image-guided aspiration in four patients, and surgical drainage in eleven patients. Two intrapelvic pyomyositis patients expired due to sepsis. At the completion of the study, twelve patients were asymptomatic without sequel, and one patient had a recurrence.

Early mechanical complications of a multidirectional mobile-bearing total knee replacement.

Between April 2004 and July 2007, we performed 241 primary total knee replacements in 204 patients using the e.motion posterior cruciate-retaining, multidirectional mobile-bearing prosthesis. Of these, 100 were carried out using an image-free navigation system, and the remaining 141 with the conventional technique. We conducted a retrospective study from the prospectively collected data of these patients to assess the early results of this new mobile-bearing design. At a mean follow-up of 49 months (32 to 71), 18 knees (7.5%) had mechanical complications of which 13 required revision. Three of these had a peri-prosthetic fracture, and were removed from the study. The indication for revision in the remaining ten was loosening of the femoral component in two, tibiofemoral dislocation in three, disassociation of the polyethylene liner in four, and a broken polyethyene liner in one. There were eight further mechanically unstable knees which presented with recurrent disassociation of the polyethylene liner. There was no significant difference in the incidence of mechanical instability between the navigation-assisted procedures (8 of 99, 8.1%) and the conventionally implanted knees (10 of 139, 7.2%). In our view, the relatively high rate of mechanical complications and revision within 30 months precludes the further use of new design of knee replacement.

Strength of the pin-bone interface of external fixation pins in the iliac crest. A biomechanical study.

The iliac crest is a frequent insertion site for external fixation pins in treating unstable pelvic or acetabular fractures and in iliofemoral distraction for superiorly dislocated hips. The pin-bone interface is critical for the success of treatment, but studies of the iliac crest are lacking. The purpose of this study was to investigate the strength of the pin-bone interface of different pins and different insertion methods. Four types of commercial pins, Wagner pins, Orthofix cortical and cancellous screws, and AO pins, were driven into sheep iliac crests by 2 methods: the intercortical and the transcortical. Specimens were tested for pullout and bending with an Instron testing machine (Model 1343) at a extension rate of 0.02 mm/sec to failure. The results revealed that the intercortical method had a stronger pullout force than the transcortical in all types of screws (p < 0.05), probably caused by longer insertion in the bone. In the pullout tests, the Wagner pins were the strongest and the Orthofix cancellous screws were the weakest. There were no differences in bending. In the iliac crest, the intercortical method was the better way of driving pins, and the new Orthofix screws were not proven to be stronger than the Wagner pins, nor were the cancellous screws more suitable than the cortical ones.

Relationship between dynamic deformities and joint moments in children with cerebral palsy.

A relationship between dynamic flexion-extension motion ranges during walking and the magnitude of flexion and extension moments was analyzed for 38 ambulatory children with spastic cerebral palsy. Moments tending to flex the hip and the knee were more than a factor of two times greater than those occurring during normal gait. At the knee, the magnitude of the moments was related to the amount of flexion deformity, whereas at the hip there was no correlation between moment magnitude and extension motion range. The maximum dorsiflexion and plantarflexion ankle moments were of less than normal value in all deformity groupings. An understanding of the longterm influence of these abnormal moments on the terms of the progression or stabilization of the dynamic deformities during walking is an important step toward improving our understanding of and, potentially, our ability to treat patients with cerebral palsy.

Use of iliofemoral distraction in reducing high congenital dislocation of the hip before total hip arthroplasty.

The iliofemoral distraction with Wagner's apparatus was conducted in 20 adult patients with untreated unilateral congenital dislocation of the hip (Crowe group IV) before total hip arthroplasty. During the distraction period of 8 to 17 days, this technique had effectively reduced high dislocation of 4.5 cm (range, 3.5-5 cm). No pin-tract infection was encountered. Surgical difficulties in total hip arthroplasty for these patients were reduced. Potential problems, such as irreducibility, overshortening, nerve palsy, and displaced femoral fractures, were avoided. At an average follow-up period of 43 months (range, 25-63 months), all patients have excellent or good results, with an average Harris hip score of 94.3 (range, 84-100). Leg length was restored. The iliofemoral distraction is valuable prior to difficult total hip arthroplasty for high dislocation.

Intraoperative instability for developmental dysplasia of the hip in children 12 to 18 months of age as a guide to Salter osteotomy.

There is still debate on the necessity of Salter osteotomy for developmental dysplasia of hip (DDH) between 12 and 18 months of age. The goals of this study were to investigate the correlating factors of intraoperative instability as a guide to the additional Salter osteotomy and to evaluate the radiographic and clinical results. Stability could not be achieved in 63% of 84 hips with soft-tissue releases alone. The existence of three pathologic findings (grade of dislocation, inverted labrum, and excessive anteversion) and absence of two surgical procedures (transverse acetabular ligament incision and iliopsoas osteotomy) significantly correlates with instability. At follow-up, the acetabular remodeling with or without Salter osteotomy was similar. We conclude that the Salter osteotomy does not interfere with the acetabular remodeling and has no major disadvantages for children at that age but can help to improve the stability of the hip.

Rising from chair after total knee arthroplasty.

OBJECTIVE: This study was performed to determine the biomechanics of chair rising by patients after successful total knee arthroplasty (TKA). DESIGN: Relative full body joint positions and ground reaction forces were measured by a motion analysis system and two force plates. BACKGROUND: Chair-rise produces increased joint forces and moments compared with level walking, and it is difficult to rise from a chair for most patients with neurological or musculoskeletal abnormalities. Previous motion studies of patients after TKA had focused on gait analysis and stair climbing. METHODS: Twelve patients after successful TKA were studied while performing sit-to-stand transfer from a chair at four chair heights without the use of arm rests. The results of this group were compared with those of 12 healthy elderly subjects and 14 osteoarthritic patients before TKA. RESULTS: Compared with the healthy elderly group during chair rising, the patients after TKA had increased horizontal mass center velocity, increased vertical hip joint forces, the maximum sound-side hip extension moment, but decreased vertical mass center velocity. CONCLUSIONS: Compensatory mechanisms of chair rising were adopted by the arthritic patients before and after TKA. The mechanisms include increased forward body bending and more weight shift on the sound side.