Autologous Bone Marrow Mesenchymal Cell Induced Chondrogenesis for the Treatment of Osteoarthritis of Knee

Healthy and high quality of life has become the main issue with increasing human life span. Many biological treatments for osteoarthritis of the knee have been tried with limited success. We compared data from 7 patients who underwent total knee arthroplasty and 46 patients who underwent autologous bone-marrow mesenchymal cell induced chondrogenesis (MCIC) for osteoarthritis of grade IV of the Kellgren-Lawrence classification and grade IV of modified Outerbridge classification from 50 to 65 years of age. Clinical evaluation of the 2 groups showed significant improvement in the mean telephone Knee Society Scoring system (tKSS)-A (pain) and tKSS-B (function) scores throughout the postoperative follow-up period. There was no difference in the patients' satisfaction between the 2 groups. MCIC is a treatment option at least for delaying disease progression of osteoarthritis of the knee.

Primary Total Knee Arthroplasty for Simple Distal Femoral Fractures in Elderly Patients with Knee Osteoarthritis

PURPOSE: Primary total knee arthroplasty (TKA) can be an alternative method for treating distal femoral fractures in elderly patients with knee osteoarthritis. The purpose of this study was to evaluate the clinical and radiographic results in patients with knee osteoarthritis who underwent TKA with the Medial Pivot prosthesis for distal femoral fractures. MATERIALS AND METHODS: Eight displaced distal femoral fractures in 8 patients were treated with TKA using the Medial Pivot prosthesis and internal fixation. The radiographic and clinical evaluations were performed using simple radiographs and Hospital for Special Surgery (HSS) knee scores during a mean follow-up period of 49 months. RESULTS: All fractures united and the mean time to radiographic union was 15 weeks. The mean range of motion of the knee joint was 114.3degrees and the mean HSS knee score was 85.1 at the final follow-up. CONCLUSIONS: Based on the radiographic and clinical results, TKA with internal fixation can be considered as an option for the treatment of simple distal femoral fractures in elderly patients who have advanced osteoarthritis of the knee with appropriate bone stock.

Letter from the President of Korean Knee Society

No abstract available.

A Comparison of the Biocompatibility of Titanium-Base Alloy According to Surface Treatments / 대한정형외과연구학회지

PURPOSE: Various surface treatments are developed and adopted to get a biological fixation by the osseointegration. An anodizing treatment, used on the surface treatment of aluminium, is applied to the surface treatment of the dental implant recently. The purpose of this study was to determine the biocompatibility and osseointegration of the titanium-base alloys according to 4 different surface treatments. MATERIALS AND METHODS: Cylindrical rods were made of titanium-base alloys, and treated with machining, grit-blasted, anodizing, and plasma spray as four groups. The rods were implanted into the femur of the 8 adult dogs. Two dogs were allocated as controls. At the postoperative 1month and 9months, the histological and push-out test was done. RESULTS: No specific systemic reactions in terms of complete blood cell count, blood chemistry, urinalysis were observed. There were no tissue necrosis, foreign body reaction, and inflammatory response to the implanted rods on the histological findings. A load-displacement curve was recorded to compare an interfacial shear strength between bone and metal, the values of the grit-blasted, anodizing, and plasma-spray groups were larger than that of machining group (p0.05). CONCLUSION: The surface treatment with anodizing would be options for artificial joint because of its lower manufacturing price and excellent biomechanical and osseointegration nature.

The Efficacy of Proximal Lumbar Curve Flexibility in Patients with Main Thoracic Adolescent Idiopathic Scoliosis Treated by Selective Thoracic Fusion Surgery

STUDY DESIGN: Retrospective radiographic study. PURPOSE: To evaluate the efficacy of the proximal lumbar curve flexibility compared with the traditional whole lumbar curve flexibility in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS). OVERVIEW OF LITERATURE: Traditionally the flexibility of the whole lumbar curve was measured, and the flexibility of the proximal lumbar curve was not analyzed in any study. METHODS: Twenty-eight MT-AIS patients treated by anterior selective thoracic fusion (STF) were evaluated after mean follow-up of 50.1 months (range, 25 to 116 months). The male : female ratio was in 5 : 23. The man age at surgery was 14 years and 8 months (range, 11.4 to 18.4 years). The lumbar curve was divided into the proximal and distal curves by the lumbar apex. RESULTS: The mean final correction rates (CR)/(flexibilities) of the MT, lumbar, proximal lumbar, and distal lumbar curves were 65.2%/(50.5%), 61.9%/(92.8%), 65.3%/(90.9%), and 36.4%/(134%), respectively. With the final lumbar CR, the lumbar flexibility (r = 0.267, p > 0.05) and the proximal lumbar flexibility (r = 0.327, p > 0.05) was similarly correlated. The mean lumbar CR was similar to the proximal lumbar CR (61.9% vs. 65.3%, p = 0.305). And the correlation between the flexibility and the CR was significant only in the proximal lumbar curve (r = 0.457, p 0.05) or the distal lumbar curve (r = 0.175, p > 0.05). CONCLUSIONS: The proximal lumbar curve flexibility may be an alternative method of measuring the lumbar flexibility in MT-AIS patients treated by STF.

Triple Labral Lesion of Shoulder : A Case Report

PURPOSE: A triple labral lesion represents a combination of injuries of the anterior, posterior and superior glenoid labrum. The injury mechanism and symptoms is not completely understood. MATERIALS AND METHODS: We encountered a triple labral injury in a 39-year-old male complaining pain and active abduction difficulty after a motor vehicle accident. Currently, he does not complain any instability symptoms. The labrum was repaired using bio-absorbable suture anchors and a suture hook. RESULTS: Eighteen months following surgery, the active range of motion was restored and he had no difficulty in his daily activities.

Arthrodesis of the Knee with a Huckstep Nail Following the Treatment Failure of an Infected Total Knee Arthroplasty

We performed knee arthrodesis with a Huckstep nail in 4 patients that had failed in controlling infection after TKA. The purpose of this study is to introduce our surgical methods and report our clinical results. We retrospectively reviewed 4 patients who underwent knee arthrodesis with a Huckstep nail after the treatment failure of infection following TKA from 2003 to 2007. Mean age was 73 years (70~79 years). All patients had type II diabetes and hypertension. From primary TKA to knee arthrodesis with a Huckstep nail, patients underwent 3.2 operations (3~4 times) on average including removal of implant, synovectomy, antibiotic cement insertion, and revisional TKA. Allo-bone grafting was performed additionally in all cases to minimize lower limb shortening. Patients were evaluated clinically, hematologically and radiologically. The mean duration of follow-up was 20.2 months (12~36 months). All patients showed bony union radiologically within one year. There was no migration or loosening of a nail and screws. Limb length discrepancy was 3 cm on average. Although 1 patient complained ambulatory pain, all patients returned to ambulation without evidence of infection recurrence. Arthrodesis of the knee with a Huckstep nail for patients who had failed in controlling infection after TKA was considered effective treatment option.

Axial Plane Lumbar Responses after Anterior Selective Thoracic Fusion for Main Thoracic Adolescent Idiopathic Scoliosis

STUDY DESIGN: A retrospective radiographic study. PURPOSE: To evaluate the axial plane lumbar responses after anterior selective thoracic fusion (STF) in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS). OVERVIEW OF LITERATURE: Anterior scoliosis surgery induces more MT derotation through disc preparation than posterior surgery. METHODS: Twenty-eight MT-AIS patients treated with STF were evaluated after a minimum follow-up (FU) of 2 years. The MT and lumbar coronal angles, as well as the MT and lumbar rotational angles at the most rotated vertebrae were measured. RESULTS: At the last FU, the MT coronal correction and derotation rates were 65% and 41%, respectively. The lumbar coronal correction rate was 61% but there was minimal lumbar derotation (2%). Nine cases were decompensated (coronal balance >10 mm). After surgery, the compensated and decompensated groups showed similar MT coronal and axial correction rates. During the FU, the MT and lumbar apecies rotated in the same direction (r=0.443). In addition, significant MT derotation occurred in the decompensated group with increasing lumbar rotational correction loss. At the last FU, while the MT coronal correction was similar between the two groups, there was more MT derotation in the decompensated group. Furthermore, the MT rotational change was strongly associated with the coronal C7 plumb line position (r=0.728). CONCLUSIONS: After anterior STF in patients with MT-AIS, the final MT derotation is strongly associated with the coronal C7 plumb line position. During the FU, the excessive MT derotation in the decompensated group was attributed to excessive lumbar rotational correction loss.

Factors affecting Fixation Failure in Treatment of Intertrochanteric Fracture of the Femur by Dynamic Compression Hip Screw

PURPOSE: The purpose of this study was to analyze the factors affecting fixation failures of intertrochanteric fractures of the femur treated by dynamic compression hip screw in elderly patients. MATERIALS AND METHODS: Between March 1999 and February 2005, we evaluated 164 cases of intertrochanteric fractures of the femur treated by dynamic compression hip screw. The failure group (group 1) contained 14 cases, and the control group (group 2) contained 150 cases. We compared the fracture pattern, type of reduction, method of fixation, tip-apex distance, location of screw within head, and presence of lateral trochanteric wall fracture between the two groups. The average patient age was 76.1 years (range 63-92) in group 1 and 75.0 years (range 63-93) in group 2. RESULTS: The mode of fixation failure in group 1 included 6 cases of nonunion, 5 cases of varus and cutting-out, 2 cases of excessive sliding of lag screw, and 1 case of plate debonding. There was a significant relationship between the fracture pattern, tip-apex distance, position of lag screw (especially the posterior location), and presence of lateral wall fracture when compared against postoperative fixation failure (P<0.05). The use of bone cement augmentation and the central location of lag screw within the head correlated with the avoidance of cutting-out of lag screw through the head. However, there was no relationship between the type of reduction, the use of additional fixation with a screw, or greater trochanter stabilizing plate when compared against fixation failure. CONCLUSION: The structural integrity of lateral wall support is thought to be an essential factor in successful treatment of unstable intertrochanteric fractures of the femur. Furthermore, methods such as concentric screw placement in the head, minimal tip-apex distance, and cement augmentation may be useful for preventing cutting-out through obtaining secure purchase of the lag screw in the head.

Activation of Transcription Factor NF-kappaB and c-Jun/AP-1 by Various Compositions of Particles in Osteoclast Precursor Cells

PURPOSE: This study was performed in order to investigate the effects of various particle preparations on NF-kappaB and c-Jun/AP-1 activity in osteoclast precursor cells. MATERIALS AND METHODS: Osteoclast precursor cells isolated from C57BL mice were treated with PMMA (polymethylmethacrylate) spheres, polystyrene, titanium particles, and retrieved metal particles from failed cementless total hip replacements. NF-kappaB and c-Jun/AP-1 DNA binding activities were analyzed using electrophoretic mobility shift assays (EMSA). RESULTS: Commercially available PMMA and polystyrene spheres routinely showed negativity on endotoxin assays, but titanium particles and retrieved metal particles consistently showed positivity. PMMA spheres, with a maximal response noted at 30 minutes with an optimal concentration of 0.6 mg/ml, were potent stimulator of NF-kappaB and c-Jun/AP-1 activity in osteoclast precursor cells. Other particles (polystyrene, titanium, metal retrievals) also activated transcription factor NF-kappaB and c-Jun/AP-1 compared to controls. Endotoxin removal from retrieved metal particles diminished the biologic effect by approximately 40%. CONCLUSION: Particles of various compositions and sizes (PMMA, polystyrene, titanium, and retrieved metal particles) activated the NF-kappaB and c-Jun/AP-1 signaling pathways. This suggests that NF-kappaB and c-Jun/AP-1 may have important roles in the pathogenesis of periprosthetic osteolysis.

The Comparision of Mitigative Effect of Alendronate and Risedronate on Particle-Induced Osteolysis: in Mouse Calvarian Model / 대한정형외과연구학회지

PURPOSE: The purpose of this study was to compare the mitigative effect of alendronate and risedronate on osteolysis in the mouse calvarian model by using titanium (Ti) and polymethylmethacrylate (PMMA) particles. MATERIALS AND METHODS: Experimental mice (male C57/BL6) are divided into three groups; control, Ti particle-treated and PMMA particle-treated group. Each Ti and PMMA particle-treated group was divided into three subgroups which received no bisphosphonates, which received alendronate, and which received risedronate. We measured number of osteoclast, area of osteolysis, bone and soft tissue thickness, ratio of bone and total tissue on mid-sagittal suture area (MSSA) and compared between two groups. RESULTS: Both alendronate and risedronate had significant inhibitory effect on Ti or PMMA particle-induced osteolysis in mouse calvarian model (p<0.05). Furthermore, bisphosphonates prevented formation of particleinduced osteolysis as RANK/Fc. Risedronate had better capability for preserving bone thickness in PMMA treated mice and also showed decreased soft tissue thickness in Ti treated mice than alendronate (p<0.05). CONCLUSION: Both alendronate and risedronate may be an effective agents on mitigation of Ti and PMMA particle-induced osteolysis. However, risedronate showed better structual bone preserving capacity than alendronate in particle-treated mouse calvariae.

Treatment of Metacarpal Fractures using Transverse Kirschner-wire Fixation / 대한정형외과학회잡지

PURPOSE: To analyze the clinical results of transverse Kirschner (K)-wire fixation for metacarpal fractures. MATERIALS AND METHODS: Between May 2002 and May 2005, thirty-four cases (thirty-nine fingers) of unstable metacarpal fractures underwent a closed reduction and transverse K-wire fixation. The neck, shaft and base fractures of the metacarpals except the thumb were included. The follow-up period ranged from 12 months to 3 years and 4 months (mean; 2 years and 1 month). Interfragmentary fixation was performed on 24 cases. A short arm splint was maintained until postoperative 4 weeks, after which the full range of motion was permitted. The K-wires were removed after achieving the full-range of motion or pin-site infection. RESULTS: At the last follow-up, there was no limitation of motion and discomfort during the daily living activities. Five cases had skin problems around the tip of the K-wire. All cases, except for three cases with angulation over 20 degrees, had achieved the union under five degrees (average 3.24 degrees dorsal angulation). Three cases had minimal rotational deformities but they did not complain of discomfort. The one case of nonunion, in whom the K-wires had been removed four weeks after surgery, underwent plate fixation and a bone graft. CONCLUSION: Transverse K-wire fixation and additional interfragmentary fixation of the metacarpal fractures can allow the full range of motion without the need to remove the K-wires. The clinical results were excellent.

Sagittal Plane Lumbar Responses after Anterior Selective Thoracic Fusion for Main Thoracic Adolescent Idiopathic Scoliosis

STUDY DESIGN: A retrospective radiographic study. PURPOSE: To verify the correlation of sagittal and coronal plane changes after selective thoracic fusion in main thoracic (MT) adolescent idiopathic scoliosis (AIS). OVERVIEW OF LITERATURE: Sagittal plane deformity is known to be essential in the evolution of scoliosis. METHODS: Twenty-eight MT AIS patients treated by anterior selective thoracic fusion were evaluated after minimal follow-up of two years. The unfused lumbar area was divided into proximal and distal parts by the lumbar apex in the coronal plane, and into proximal and distal lumbar lordosis by L2 in the sagittal plane. Surgical motion (the difference between preoperative and postoperative values) and follow-up motion (the difference between postoperative and the last follow-up values) were compared. RESULTS: Immediately after surgery, as thoracic kyphosis increased, lumbar lordosis decreased (r=0.734); proximal lumbar lordosis increased, and distal lumbar lordosis decreased. The proximal lumbar area was mobilized in the sagittal plane, and was straightened in the coronal plane. However, the distal lumbar area was stabilized in the sagittal plane, and showed resistant motion against MT translation in the coronal plane. The surgical motion was correlated to the follow-up motion, i. e., was regulated during follow-up, and the regulatory motion was more precise in the distal than proximal lumbar area in both sagittal and coronal planes. CONCLUSIONS: Sagittal and coronal motions were co-related; optimal sagittal motions were necessary for optimal coronal motions after anterior selective thoracic fusion for MT AIS. Proximal and distal lumbar motions were different for different roles; the proximal lumbar area played a role as a bumper to absorb the MT translatory force, and the distal lumbar area played a role of resistance against MT translation.

Arthroscopic Treatment of Pigmented Villonodular Synovitis of the Knee / 대한정형외과학회잡지

PURPOSE: To evaluate the efficacy of arthroscopic synovectomy through the direct posterior-posterior approach in pigmented villonodular synovitis (PVNS) of the knee. MATERIALS AND METHODS: Between January 1997 and May 2004, twenty-one patients underwent an arthroscopic synovectomy for PVNS of knee. The mean follow-up period was 35 months. The arthroscopic and MRI findings revealed the localized form of PVNS in six patients and the diffuse form in fifteen patients. All patients underwent an arthroscopic examination and synovectomy through the direct posterior-posterior approach. The clinical results were evaluated by the range of motion, Lysholm knee score, and the knee pain score using the visual analogue scale (minimum 0-maximum 10). RESULTS: Among the fifteen cases with the diffuse form, three cases (14%) recurred and had secondary arthroscopic total synovectomy. One cases recurred again. Therefore, radiation therapy was performed. The Lysholm knee score improved from 62.5 to 87.3, and the VAS score improved from 5.9 to 1.8. Three patients had a mild limitation in knee motion. However, the others had full range of motion of the knee at the last follow-up. CONCLUSION: Arthroscopic synovectomy through the direct posterior-posterior approach could be a useful method for the treatment of PVNS of the knee, and can be used as an effective therapeutic tool particularly in posteromedial or posterolateral lesions.

Treatment of Femoral Neck Fractures in Patients with Ischemic Heart Disease by Cemented Hemiarthroplasty

PURPOSE: There is a controversy about whether the use of polymethylmethacrylate (PMMA) in orthopedic reconstructive surgery can increase the possibility of cardiovascular dysfunction. This study was undertaken to determine if cemented hemiarthroplasty is safe for treating femoral neck fracture in patients with ischemic heart disease. MATERIAL AND METHODS: Between March 1999 and February 2004, we performed cemented hemiarthroplasties for displaced femoral neck fractures in 158 consecutive patients. This retrospective study consisted of 44 patients with ischemic heart disease (group 1) and 58 age matched control patients (group 2). We compared the mortality rate, the incidence of deep vein thrombosis (DVT), pulmonary embolism, cerebrovascular disease, dislocation and deep infection, the amount of postoperative blood loss and the grade of cementation according to the schema of Barrack on the radiograph between the two groups. RESULTS: No difference was found in the perioperative mortality rate, the deep infection rate, the incidence of DVT or pulmonary embolism, the newly developed heart ischemic events or brain hemorrhagic lesions between the two groups. But there was a greater incidence of dislocation related to weakness from past brain ischemic lesion and the newly developed brain ischemia in group 1 than in group 2 (p<0.05). More importantly, six patients in group 1 had transient symptoms of dyspnea, signs of hypotension and bradycardia within two days postoperatively, which raises suspicions of embolic phenomenon, even though this was not confirmed. CONCLUSION: Close and careful observations should be done for the occurrence of dislocation related to previous brain ischemia, or newly developed brain ischemic lesion or embolic phenomenon. Appropriate thromboprophylaxis is necessary in patients with ischemic heart disease after cemented hemiarthroplasty for the treatment of femoral neck fracture.

Preoperative Use of 3D Computed Tomography for Prediction of Fracture Stability in Treatment of Jensen Type 4 Intertrochanteric Fractures of the Femur

PURPOSE: We wanted to evaluate the efficacy of performing preoperative 3D computed tomography scanning in treatment of Jensen's type 4 intertrochanteric fractures of the femur for predicting the stability of fractures. MATERIALS AND METHODS: From March 2001 to February 2005, 56 patients, who were at least 65 years old, with Jensen's type 4 intertrochanteric fractures were included in our study. We divided them into two groups; group 1 (the control group, 34 cases) and group 2 (the experimental group, 22 cases). The average age of the patient was 78.7 years (range: 65~95) in group 1 and 77.8 years (range: 65~89) in group 2. We measured the volume of each fragments in the 3-part fractures by performing preoperative 3D computed tomography scanning. The criteria of unstable fracture were that the ratio of the volume of the greater trochanter to the the volume of the proximal femur was less than 25% and the ratio of the volume of the lesser trochanteric fragment to the volume of the greater trochanter was above 0.5. Dynamic compression screws alone were used in 30 cases (group 1) and 19 cases (group 2). Additional fixation by employing a greater trochanter stabilizing plate was done in 4 cases (group 1) and in 3 cases (group 2). We compared the radiological results and the rates of the fixation failure at the last follow-up between the two groups. RESULTS: There were four cases of fixation failure in group 1: varus &cut-out (2 cases), nonunion (1 case) and excessive backout of the screw (1 case). But there was no case of fixation failure in group 2. The neck shaft angle was 131.6+/-5.2 in group 1 and 134.7+/-4.3 in group 2. The sliding length of the lag screw was 8.4+/-3.2 mm in group 1 and 5.5+/-2.7 mm in group 2 (p<0.05). CONCLUSION: The volumetric measurement of each of the fragments in Jensen's type 4 intertrochanteric fracture by preoperative 3D computed tomography scanning for predicting the stability of fracture is useful in preventing fixation failures. Yet the radiation hazard or cost effectiveness should be considered for the risk vs benefit.

Complete Rupture of Sciatic Nerve by Protruded Kuncher Nail in Pelvic Bone Fracture: A Case Report

Rupture of sciatic nerve is a rare injury in minimally displaced pelvic bone fracture. We report one case of complete rupture of sciatic nerve that were resulted from the extremely protruded Kuncher nail inserted before accident and the preexisting heterotopic ossification with a review of the relevant literature.

Simultaneous Dorsal Dislocation of Interphalangeal Joints in the Same Finger: Two Case Report

We treated 2 cases of simultaneous dorsal dislocation of interphalangeal joints in the 5th finger. One case was injured by herperextension during basketball, and treated by open reduction and K-wire fixation. Another case was injured by industrial accident, and treated by splint for 1 week.

Preventive and Mitigative Effects of Alendronate on Osteolysis induced by Particulate Debris: Quantitative and Comparative Analysis Using Mouse Calvarial Model / 대한정형외과학회잡지

PURPOSE: Wear particle induced osteolysis is a serious complication in total joint arthroplasty. The purpose of this study was to compare the preventive and mitigative effects of alendronate on particle induced osteolysis among particles using mouse calvarial model. MATERIALS AND METHODS: Seventy-two mice were randomized into sham group, Ti6Al4V group, CoCr- Mo group and Ultra High Molecular Weight Polyethylene (UHMWPE) group according to the particles treated to the calvarial tissues. Each group was divided into control subgroup which received no alendronate, preventive subgroup which received alendronate for 4 weeks after particle distribution and therapeutic subgroup which received alendronate for 3 weeks after 1 week delay from particle distribution. We evaluated the effects quantitatively using histomorphometry. Number of osteoclast, fibrous thickness, eroded bone surface area, bone thickness and bone volume were measured and compared. RESULTS: Alendronate showed significant preventive and mitigative effects on osteolysis induced by Ti6Al4V particles and showed significant preventive and somewhat less mitigative effect on osteolysis by CoCrMo particles. On UHMWPE particles, alendronate showed no preventive and mitigative effects. CONCLUSION: Alendronate may be useful in preventing osteolysis induced by metal particles but had no effect on ostelysis induced by UHMWPE particles.

The Role of Lateral Buttress in Treatment of Jensen type 4 Intertrochanteric Fractures of the Femur using Dynamic Compression Hip Screw in the Elderly / 대한정형외과학회잡지

PURPOSE: To investigate the effect of lateral buttress on the fracture healing of Jensen type 4 intertrochanteric fracture of the femur treated by dynamic compression hip screw (DCS) in elderly patients, retrospectively. MATERIALS AND METHODS: From March 1999 to February 2003, 54 patients, older than 65 years, of Jensen type 4 intertrochanteric fractures of the femur treated by DCS were included. The relationship between the structual integrity of lateral buttress measured by proximal-medial fragment angle (PMFA) and postoperative neck-shaft angle, penetrating length of lag screw, the sliding length and incidence of fixation loss were evaluated. RESULTS: Among 38 patients of group II (PMFA above 50 degree), 6 cases (15.8%) including 4 cases of cutting out of lag screw from femoral head, 1 case of nonunion and 1 case of excessive extrusion of lag screw failed radiologically. But there was no fixation loss case in 16 cases of group I (PMFA 50 and below 50). The neck-shaft angle in last follow-up was 138.1 degree in group I and 132.1 in group II. The sliding length of lag screw was 7.0 mm in group I and 12. 5 mm in group II (p<0.05). CONCLUSION: Preoperative evaluation of intactness of lateral buttress measured by proximal-medial fragmentary angle is an useful method in treatment of Jensen type 4 intertrochanteric fractures treated by DCS in elderly patients.