Role of the Y5 neuropeptide Y receptor in feeding and obesity

Removal of a plate from the distal femur creates a risk of fracture through the screw holes. This is a particular concern when a total knee arthroplasty is present because supracondylar fracture may occur with minimal trauma. A patient who presents after prior plating of a distal femur fracture with osteoporosis, retained hardware associated with pain, and gonarthrosis severe enough to warrant total knee arthroplasty is often difficult to manage. Prophylactic intramedullary rodding is a well-accepted method of treating pathologic stress risers in the femur. An intramedullary rod can be inserted into the femur at the time of total knee arthroplasty. This method permits simultaneous plate removal and total knee arthroplasty while protecting the femur from postoperative fracture.     

Investigation of the usefulness of CYFRA 21-1 as a tumor marker in squamous cell carcinomas of the head and neck

Compressive contact stress between the patella and the anterior femur and between the quadriceps tendon and anterior femur was measured before and after total knee arthroplasty in 5 cadaver knee specimens using a digital electronic sensor. Contact stresses were measured in the normal knee and after total knee arthroplasty with an unresurfaced patella, a dome-shaped patella, and a conforming patella. Patellofemoral contact stresses did not change significantly after total knee arthroplasty when the patella was not resurfaced, but they increased significantly after the patella was resurfaced with both the dome-shaped and the conforming components. The conforming patella had the highest contact stresses because it tilted at flexion angles greater than 90 degrees and applied load to a small area on the superior portion of the patellar component. The conforming patella markedly decreased tendofemoral contact force because the thicker superior pole of the patella tented the quadriceps tendon at flexion angles greater than 120 degrees. This further increased patellofemoral contact force in deep knee flexion.     

Proximal femur fractures after free vascularized fibular grafting to the hip

The management of symptomatic femoral head osteonecrosis in young, active patients is troublesome and controversial. At the authors' institution, 707 consecutive free vascularized fibular grafts were performed for femoral head osteonecrosis between October 1979 and October 1995. Patients who underwent this procedure were at increased risk for proximal femur fractures because of the 16 to 21 mm core drilled through the lateral femoral cortex for removal of the avascular bone and placement of the fibular graft. An ongoing prospective database of patients who underwent this procedure was accessed to determine the incidence of and factors associated with postoperative subtrochanteric femur fractures. Eighteen subtrochanteric fractures occurred for an overall incidence of 2.5%. All fractures occurred through the core decompression site in the lateral femoral cortex. The treatment was nonoperative in seven patients and operative in 11. Fourteen of 18 fractures (77%) healed with an average of 4.1 months until radiographically documented union. Four fractures had nonunions develop, three of which later healed with bone grafting and internal fixation, whereas the fourth eventually required conversion to total hip arthroplasty. Twelve fractures in 251 patients occurred when the weightbearing regimen was touchdown weightbearing for the first 6 weeks and five fractures in 456 patients occurred when the weightbearing regimen was changed to nonweightbearing. The results indicate that nonweightbearing in the immediate postoperative period is associated with the lowest fracture rate.     

From bacteriophage lambda to nonlinear dynamics

We describe a successful treatment, intramedullary fibular grafting, for a patient with a supracondylar fracture of the femur following total knee arthroplasty in which the fracture region was comminuted and a segmental large bone defect was present. Free autogenous fibular was inserted into the medullary cavity from the intercondylar region and fixed to the proximal fragment of the femur with augmented fixation using a small plate and screws. Our procedure makes it easy to perform large segmental bone grafting and internal fixation at the same time for such a condition.     

Fractures after total knee joint endoprosthesis. Results of treatment with various stabilizing methods

In 20 patients with a fracture of femur or tibia 5.2 years after arthroplasty of knee the results of the operative treatment are presented. The results show that especially bone damaging diseases as rheumatoid arthritis, osteoporosis and the loosening of the endoprosthesis are favorable for the fracture during the follow-up. The conclusion of the investigation shows that in younger patients the external fixation by plates and screws is the preferential treatment, in elderly people or comminuted fracture an internal fixation, also in combination with an additional osteosynthesis, allows a fast mobilization. The number of observed complications is higher than in primary knee arthroplasty, the full weight bearing 1st delayed. The rate of further operations and unsatisfactory results is also higher being affected by the high mean age of the operated patients (73.4 years). The possible use of a total femur implant must be discussed critically because only an individual production can avoid further damage of the parts of the joint that were not concerned by the fracture.     

Intramedullary versus extramedullary fixation of subtrochanteric fractures. A biomechanical study

We compared two different subtrochanteric fracture fixation techniques, an intramedullary hip screw system (IMHS) and an extramedullary, dual sliding screw-plate system (MSP), to determine relative fixation stability. 6 matched pairs of osteosynthesized osteopenic cadaver femurs were axially loaded to 1000 N with concurrent, simulated abductor forces of 0%, 50%, or 86% of the applied head force. The initial loading sequence was made with uniaxial dynamization--the lag screw of the MSP locked and distal locking of the IMHS nail. Femoral head displacement and medial femoral strain were measured for intact femur controls, after fixation of a 2-part reverse oblique subtrochanteric fracture and finally a 3-part reverse oblique subtrochanteric fracture with a lateral wedge defect. The samples were then loaded at 750 N for 10(4) cycles with both devices uniaxially locked, followed by 10(4) cycles with both devices fully biaxially dynamized (unlocked). For the 2-part subtrochanteric fracture pattern, both devices exhibited similar inferior displacements of the femoral head (average 2.0 mm) and medial femoral strain (approximately 70% of intact). Increasing abductor forces decreased medial compressive strain but did not significantly affect head displacement. For the 3-part fracture model, the MSP demonstrated significantly less inferior displacement of the head (1.6 mm vs. 2.1 mm) and both devices demonstrated significantly decreased medial strain. After cycling, head displacement increased approximately 50% in both devices and medial strain increased slightly. After unlocking and cycling, the MSP group showed significant lateral displacement of the proximal fragment. The IMHS and MSP devices provide similar stability for fixation of 2-part and 3-part reverse oblique subtrochanteric fractures. In a biaxially dynamized, 3-part reverse oblique fracture, displacement of the proximal fragment can occur with the MSP.     

Lunate and perilunate dislocation

BACKGROUND: Patellar problem is an important cause of nonseptic failure of the current condylar design of total knee arthroplasties. Patellar dislocation after total knee arthroplasty is infrequent but can cause disabling symptoms. METHODS: From March, '84 to July, '92, 1652 total knee arthroplasties were performed at this Hospital. Of these 1100 knees in 978 patients were available to be followed up regularly at the Outpatient Department. Eleven cases of patellar dislocation after total knee arthroplasty were encountered during follow-up. Among these patients, nine patients had received operation at this Hospital; the other two patients had been referred here by the other hospitals. All 11 patients had been treated with surgical methods: proximal realignment of the quadriceps alone in 6 knees, lateral retinacular release combined with revision of the malaligned components in 2 knees, combined proximal and distal realignment in 2 knees and patellar tendon transfer in 1 knee. RESULTS: After an average follow-up of 21.8 months, from April, '84 to April, '93, there was one redislocation, unfortunately caused by trauma. Using the average knee rating scale of the Hospital for Special Surgery, New York, USA, the results of 90.5 were satisfactory and encouraging. CONCLUSIONS: Patellar dislocation after total knee arthroplasty can cause disabling symptoms, including pain, weakness, limited range of motion, extension lag and difficulty when climbing up or down stairs. The cause of patellar dislocation after total knee arthroplasty was error in surgical technique in this series. Revision of the component should be performed in those with malaligned component. Proximal realignment is recommended in those with quadriceps imbalance. Distal realignment is recommended only when proximal realignment alone has failed to restore proper patellar tracking, this should be carried out with great caution due to the potential for serious complications.     

Cementless implant composition and femoral stress. A finite element analysis

Proximal atrophy and thigh pain are recognized problems with some cementless femoral stems in total hip arthroplasty. It is thought that reduced femoral stress from alterations in load transfer caused by an intramedullary stem contributes to proximal femoral atrophy. An increase in flexural rigidity and bone stress near the stem tip is thought to contribute to thigh pain. A three-dimensional finite element analysis study was performed to calculate stresses in the proximal femur and bone near the stem tip before and after implantation of a collared, proximally coated, cementless femoral prosthesis. The influence of prosthetic material was examined by changing implant composition from cobalt chrome to titanium alloy and leaving all other parameters constant. Femoral stress was increased twofold immediately below the collar with the titanium implant compared with the cobalt chrome. However, the proximal femoral stress in the titanium implanted model was still 1/10 that in the corresponding region of the unimplanted femur model. At the stem tip, as much as a 30% reduction in femoral stress was seen with the titanium stem compared with the cobalt chrome. These findings suggest biomechanical evidence of an advantage for titanium as an implant material compared with cobalt chrome for cementless femoral stems.     

Nonselective debridement and antimicrobial cleansing of a venting ductal breast carcinoma

Supracondylar femur fractures above a total knee replacement are rare injuries that may be challenging to treat. We present a case of an elderly woman whose supracondylar femur fracture was not deemed amenable to conventional treatment. This patient underwent fixation of her femur fracture above a total knee replacement using an Ilizarov external fixator. The fixator was removed at 10 weeks, at which time the fracture was solidly healed. At the most recent follow-up, the patient is 19 months postinjury. She is fully weight bearing without walking aids and has a knee range of motion of 0 degree to 110 degrees.     

Subtrochanteric femoral shortening osteotomy in total hip arthroplasty for high-riding developmental dislocation of the hip

A surgical technique, which uses a transverse osteotomy, for subtrochanteric femoral shortening and derotation in total hip arthroplasty for high-riding developmental dislocation of the hip is described. Anteversion is set by rotating the osteotomy fragments, and torsional stability is augmented with allograft struts and cables when indicated. Eight patients with 9 total hip arthroplasties were followed for an average of 43 months (range, 24-84 months). Good to excellent results were obtained in 87% of patients (7 of 8). Eight of 9 osteotomies (89%) demonstrated radiographic evidence of healing at an average of 5 months. One patient had an asymptomatic nonunion of the osteotomy site but still had a good overall clinical result. Another patient suffered fatigue failure of a distally ingrown porous device, which necessitated revision total hip arthroplasty 18 months after surgery. Subtrochanteric osteotomy in total hip arthroplasty for developmental dislocation of the hip allows for acetabular exposure and diaphyseal shortening while facilitating femoral derotation. Furthermore, proximal femoral bone stock is maintained and some of the potential complications of greater trochanteric osteotomy may be avoided.     

2-stage reimplantation for infected total knee replacement

Between 1977 and 1983, 64 infected total knee replacements in 60 patients were treated with a 2-stage protocol for reimplantation. The clinical results and survivorship were determined at an average followup of 7.5 years (range, 2-17 years). Surgical protocol included removal of the prosthesis and all cement with thorough debridement of bone and soft tissues. This was followed by 6 weeks of parenteral antibiotics and then reimplantation of a new prosthesis. At followup, 6 knees (9%) had become reinfected, but only 2 with the same organism. Four knees had been revised: 3 for aseptic loosening and 1 for a periprosthetic femur fracture. Two other knees were impending failures due to aseptic loosening. The average Hospital for Special Surgery knee score was 78 points with 18 excellent, 28 good, 13 fair, and 5 poor results. Seventy-eight percent of patients were satisfied with the overall result of their reimplanted prosthesis and 95% think that they made the right decision in undergoing total knee arthroplasty. The 10-year predicted survivorship of 2-stage reimplantation is 77.4%. Two-stage reimplantation with a 6-week course of parenteral antibiotics is an effective means to eradicate deep infection and to provide a functional knee. The long term functional results and overall survivorship are comparable with the results of revision of aseptic failed total knee arthroplasty.     

Static and dynamic function of the lower esophageal sphincter before and after laparoscopic Nissen fundoplication

SUBJECT: We analysed the periprosthetic bone mineral density (BMD) in a prospective longitudinal study over two years after operation and in a separate cross-sectional study more than five years after implantation of cementless total hip arthroplasty (CLS-stem, Mecron threaded acetabular cup) by using dual-energy X-ray absorptiometry (DEXA). MATERIALS AND METHODS: In n = 53 patients (29 women, 24 men) we analysed the periprosthetic BMD prospectively in certain periods. All patients had an uncomplicated postoperative course and good clinical outcome (Merle d'Aubigne score > 12). In the cross-sectional study we analysed 23 patients (13 women, 10 men). Regions of Interest (ROI) were defined according to Gruen et al. for the periprosthetic femur and to De Lee and Charnley for the periprosthetic acetabulum. RESULTS: BMD significantly decreases in the periprosthetic femur as well as in the periprosthetic acetabulum during the first three months. In men BMD reaches its lowest values between six months (femur) and one year (acetabulum) after operation and then increases to 96.2% at the femur and 93.8% at the acetabulum. In women BMD decreases during the entire follow-up to 89.4% at the periprosthetic femur and 80.0% at the periprosthetic acetabulum. In the proximal zones 1 and 7 of the femur and the cranial-medial zone II of the acetabulum we observed the highest decrease of mineralisation. More than five years after implantation of the prosthesis BMD in the femur showed only little changes. On the other side BMD around the threaded acetabular cup significantly decreased to 67.4% in women and 79.1% in men. CONCLUSION: The results reflect the different stress on the periprosthetic bone after implantation of the prosthesis and fit to earlier reported good clinical results of the CLS-stem and to increased loosening rate of threaded acetabular cups after five years. Analysing changes of mineralisation in cementless total hip arthroplasty DEXA together with the analization scheme according to Gruen at the femur and to De Lee and Charnley at the acetabulum is a useful method and has been reliable in clinical practise.     

Molecular cloning in Arabidopsis thaliana of a new protein phosphatase 2C (PP2C) with homology to ABI1 and ABI2

Trapeziectomy, ligament reconstruction and tendon interposition arthroplasty is one of the most commonly performed procedures to address pain and instability due to osteoarthritis at the basal joint of the thumb. To determine the effect of stress on first metacarpal subsidence, 15 ligament reconstruction and tendon interposition basal joint arthroplasties were evaluated after a mean follow-up of 32 months. Radiographs were obtained of the arthroplasty at rest and then with maximal effort key pinch stress, which is known to subject the first carpometacarpal joint to considerable axial compression stress. Compared with the preoperative x-rays, the first metacarpal had subsided 21% of the arthroplasty space at rest. Under stress, the first metacarpal was found to subside another 10.5% in height. No subluxation of the metacarpal base could be detected. Key pinch strength improved 17% from the preoperative strength. Tip-to-tip pinch strength improved 17% from the preoperative measurement. Grip strength improved 17% from the preoperative measurement. Grip strength was 9% greater than the preoperative grip strength. There was no statistical association between the amount of first metacarpal subsidence and follow-up key pinch, tip pinch, or grip strength. With axial compressive loading of the arthroplasty, such as in lateral pinch, there is some further proximal migration of the first metacarpal, but this is minimal and does not correlate with functional outcome.     

Tumor endoprosthesis in malignant bone tumors

In the Department of Orthopedics at the University of Vienna, tumor endoprostheses have been implanted after resections of tumors of the upper extremities since 1974 and of the knee joint since 1976. For replacement of the humerus after tumor resection, a system of modular tumor endoprostheses was developed very early. Initially, it was ceramic and later on made of titanium alloys, which were also implanted in combination with custom-made prostheses with cementless stem-plate fixation in 57 patients until February 1990. In 43 of these patients (75.4%) adequate resection (2 radical and 41 wide) had been performed. Of 49 patients with a follow-up period of at least 24 months, 36 patients had a mean disease-free survival time of 106.1 months. Between 1976 and 1981, 16 custom-made endoprostheses were used after tumor resection of the knee joint. Since 1982 we have used a modular system of tumor endoprostheses suitable for replacement of the proximal and distal femur, proximal tibia, total femur and total knee joint. Of 75 patients who had been operated on up to February 1990, 67 patients (89.3%) had undergone adequate resection (2 radical and 65 wide). Out of 32 of these patients, 24 (75%) exhibited a disease-free survival time of at least 24 months (mean 48.2 months). Out of 213 patients with resection/reconstruction (160 endoprostheses), 77.8% had a survival time of at least 24 months, a results which is considerably better than in 146 patients with amputation in which case the respective value was 69.4%.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of femoral component position on the kinematics of total knee arthroplasty

In a laboratory study using seven fresh-frozen anatomic specimen knees, the effect of total knee arthroplasty on the three-dimensional kinematics of the patella, femur, and tibia were measured. Experiments were performed in the intact knee, after division of the anterior cruciate ligament (ACL), after total knee arthroplasty, and after 10 degrees internal rotation, 10 degrees external rotation, 5-mm medial shift, and 5-mm lateral shift of the femoral component on the femur. The presence of a high lateral ridge on the anterior surface of the femoral component effectively prevented patellar subluxation or dislocation, but displaced and tilted the patella medially. Internal rotation or medial displacement of the femoral component exaggerated this medial patellar displacement and shift. External rotation of the femoral component corrected it, except at flexion angles greater than 100 degrees, where the femur was shifted medially on the tibia and externally rotated 15 degrees. This combination produced a net 10-mm medial displacement of the patella relative to the tibia at 120 degrees knee flexion. Lateral placement of the femoral component compensated for the effect of the high lateral ridge and allowed more normal patellar tracking while allowing tibiofemoral motions similar to those seen after sectioning of the ACL. The kinematics of the patellofemoral and tibiofemoral joints were not reproduced with a total knee prosthesis that sacrifices the ACL. When using a prosthesis with a high lateral ridge, lateral placement of a femoral component prevented patellar dislocation and allowed patellar tracking patterns similar to those seen in the intact knee without further altering tibiofemoral motions.     

Aerial fallout of DDT in southern California

Ender's method of intramedullary fixation of intertrochanteric and subtrochanteric fractures is described. Ender's nail is a pre-bent flexible steel nail with a diameter of 4.5 millimeters. Three to five of these nails are inserted from a small incision proximal to the medial epicondyle of the femur into the medullary canal. They are passed through the femur across the fracture site and into the head of the femur, where they diverage. They are in the lines of force and therefore are not subjected to bending moments. The fracture fixation allows immediate weight-bearing. This method of fixation was used in a series of 203 patients. Their average age was sixty-eight years; the mortality rate was 10.3 per cent. In 3.9 per cent superficial infections occurred, but in no case was there a deep infection involving the bone. Functional return (walking) was achieved in all of the survivors who were able to walk at the time of injury, and there were no nonunions.     

Adenocarcinoma combined with malignant peripheral nerve sheath tumor of the gallbladder

Adenocarcinoma of the gallbladder combined with a malignant peripheral nerve sheath tumor (MPNST) in the gallbladder in an 81-year-old woman is reported. The resected gallbladder showed two distinct tumor components, the epithelioid type of MPNST and adenocarcinoma with areas of mucin production. Although the immediate postoperative course was uneventful, a pathologic fracture of her right upper femur developed 4 months after the cholecystectomy. The pathology was determined to be a feature of metastatic MPNST rather than of adenocarcinoma. A whole body bone scan revealed multiple metastases, including the left parietal skull, left ninth rib, seventh thoracic vertebra, and right upper third of the femur. Despite cholecystectomy and postoperative irradiation therapy, she died 6 months after diagnosis of the tumor. Without an autopsy the primary site of the MPNST was unknown. We found that the prognosis was very poor in patients with distal metastatic MPNST, especially in older patients.     

Nonunion after a tibial shaft fracture complicating tibial tubercule osteotomy

Tibial shaft fracture after tibial tubercle osteotomy in total knee replacement is a rare complication. We report on a 67-year-old man who had a knee revision arthroplasty in which a long tubercle osteotomy was performed to facilitate exposure. Three weeks after surgery, he presented with a transverse shaft fracture, which became a nonunion requiring surgical management. This shaft nonunion and its solution after tibial tubercle osteotomy is discussed as well as relevant literature.     

Bone allografts are immunogenic and may preclude subsequent organ transplants

The authors report a case of a 41-year-old woman with diabetes and chronic renal failure in whom antihuman leukocyte antigen antibodies developed after she received a frozen bone allograft that limited her access to organ donors. The patient had a chondrosarcoma of the right distal femur. A wide resection with segmental total knee arthroplasty was followed by a revision using a composite bone allograft prosthesis. After revision, broadly reactive lymphocytotoxic antibodies developed in the patient. The patient's panel reactive antibody level rose from 28% to a peak of 70%. Panel reactive antibody expresses the percentage of a panel of human leukocyte antigen type T lymphocytes from 40 individuals (representative of all human leukocyte antigen Class I histocompatibility antigens) to which antihuman leukocyte antigen Class I lymphocytotoxic antibodies have developed in the recipient as measured by the antiglobulin crossmatch method. The specificity of the patient's primary antibody is found in 45% of donors available in Illinois since 1988 (N = 1606). Because a positive crossmatch precludes kidney and pancreas transplantation, at least 45% of cadaver organ donors were excluded from use for this patient. This is an unusual case that focuses on the potential impact of bone allografts in patients who may need subsequent organ transplantation.     

Simultaneous bilateral versus unilateral total knee arthroplasty. Outcomes analysis

One hundred consecutive, primary simultaneous bilateral total knee arthroplasties were prospectively compared with 100 consecutive, primary unilateral total knee arthroplasties in reference to relative risk, complications, cost, and need for rehabilitation. All procedures were performed using identical preoperative, intraoperative, and postoperative protocols. Postoperative confusion was approximately four times greater in the simultaneous bilateral total knee arthroplasties group (29% versus 7%), which was thought to represent an increased incidence of fat embolism. Cardiopulmonary complications were approximately three times greater after simultaneous bilateral total knee arthroplasties (14% versus 5%), and most commonly involved arrhythmias. The increased stress on the cardiopulmonary system with simultaneous bilateral total knee arthroplasties may make this procedure contraindicated in certain patients with preexisting disease. There was an approximately 17 times greater need for banked blood in the simultaneous bilateral total knee arthroplasties group (17% versus 1%), which is alarming given the persistent concerns of transfusion related disease transmission. Although the length of hospitalization was similar (6.4 days simultaneous bilateral total knee arthroplasties versus 6 days unilateral total knee arthroplasty), 89% of the patients in the simultaneous bilateral total knee arthroplasties group required a rehabilitation stay versus 45% of the patients in the unilateral total knee arthroplasty group. Total hospital charges averaged $53,168 for simultaneous bilateral total knee arthroplasties versus $32,598 for unilateral total knee arthroplasty. Total rehabilitation charges were similar. The relative cost savings implicit by doing simultaneous bilateral total knee arthroplasties seem to be at least partially offset by the approximately two times greater need for rehabilitation in this group. The true safety, efficacy, relative risk, and total cost analysis of simultaneous bilateral total knee arthroplasties demands further critical evaluation.