[Replacement of hip joints and knee joints with internal prosthesis].
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Age Factors↗
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Efficacy of sparfloxacin and autoradiographic diffusion pattern of [14C]Sparfloxacin in experimental Staphylococcus aureus joint prosthesis infection.
Using a new rabbit model of methicillin-susceptible Staphylococcus aureus knee prosthesis infection, we compared the efficacies of sparfloxacin (50 mg/kg of body weight subcutaneously, twice a day) and pefloxacin (50 mg/kg subcutaneously, twice a day). A partial knee replacement was performed with a silicone implant fitted into the intramedullary canal of the tibia, and 5 x 10(7) CFU of methicillin-susceptible S. aureus was injected into the knee. The 7-day treatment regimen was started 15 days later. The MICs and MBCs of sparfloxacin and pefloxacin were, respectively, 0.06 and 0.25 microgram/ml (MIC) and 0.25 and 1 microgram/ml (MBC). The peak levels of sparfloxacin and pefloxacin in serum were 3.6 and 21 micrograms/ml, respectively. Three weeks after the end of treatment, animals were sacrificed and tibias were removed, pulverized, and quantitatively cultured. In contrast to pefloxacin (3.61 +/- 1.64 log10 CFU/g of bone), sparfloxacin significantly reduced the bacterial density (2.12 +/- 1.1 log10 CFU/g of bone) (P = 0.01) in comparison with the level in controls (4.59 +/- 1.21 log10 CFU/g of bone), without selection of resistant variants. Sparfloxacin was significantly more effective than pefloxacin (P = 0.025). The autoradiographic pattern of [14C]sparfloxacin diffusion was studied in noninfected animals with prostheses and in infected animals 15 days after inoculation. Sixty minutes after completion of infusion of 250 microCi of [14C]sparfloxacin, in infected animals the highest levels of radioactivity were detected around the prosthesis, in femoral cartilage, and in articular ligaments. Radioactivity was slightly less intense in bone marrow and muscles and was very weak in compact bone. The distribution of sparfloxacin in uninfected rabbits was similar. Thus, sparfloxacin may represent a valid alternative therapy in these infections provided that it is carefully monitored for potential side effects.
Animals↗
Quadriceps function after TKA--an in vitro study in a knee kinematic simulator.
OBJECTIVE: The purpose of this in vitro study was to investigate the amount of quadriceps force required to extend the knee during an isokinetic extension cycle before and after total knee arthroplasty. DESIGN: The magnitude of the extension torque used in simulating a constant moment extension exercise was derived from tests made using a dynamometer on patients who had received a total knee arthroplasty. Quadriceps force needed to extend the knee was measured. METHODS: Human knee specimens (n=8, mean age=65 SD 7 years, all male) were tested in a kinematic knee simulating machine untreated and after implantation of two different knee prosthesis. During simulation, a hydraulic cylinder applied sufficient force to the quadriceps tendon to produce an extension moment of 31 Nm about the knee. RESULTS: The quadriceps forces needed to extend the knee during the physiologic simulation reached levels as high as 1238.9 N (SD 46.6). After implantation the Interax-prosthesis, quadriceps force increased up to 13.9% (P=0.003), in conjunction with resurfacing of the patella 11.9% (P=0.01). With the LCS-prosthesis implanted, quadriceps force showed a somewhat smaller increase of up to 6.6% (P=0.007). RELEVANCE: The following study helps to clarify postoperative problems related to the extensor mechanisms of the knee after implantation of total knee arthroplasty.
Arthroplasty, Replacement, Knee↗
Dacron fabric-enveloped alumina ceramic prosthesis for cementless resection arthroplasty of the proximal tibia: a case report with a long-term result.
After resection of the primary lesion, the right proximal tibia of a patient with osteosarcoma was reconstructed using a Dacron fabric-enveloped alumina ceramic total knee prosthesis without cement. Dacron fabric is intended to act as a scaffold upon which connective tissue can proliferate and form new ligament and other supporting soft tissues. Usually, following wide resection of the primary lesion, the supporting system is lost. If the supporting soft tissues are not reconstructed after removal of the tumor, they will be fixed in a slackened condition and will not provide sufficient support, leading to problems of stability and function. Using alumina ceramics alone does not induce surrounding connective tissue formation; therefore, stability is not ensured. The support of the vascular tissue enables the fabric to carry out the functions of ligaments, tendons, retinaculum, periosteum, joint capsule and other supporting soft tissues. Over time, stabilization occurs, biologic fixation of the prosthesis to the supporting soft tissues is successful and the durability of the prosthesis is prolonged. Postoperative follow-up has continued for a 77-month period. At present, the patient continues to show no evidence of disease and is able to walk painlessly up and down stairs without using a knee brace or handrail. A knee brace was recommended, however, to ensure the durability of the prosthesis. Dacron fabric is useful for the repair of supporting soft tissues without significant complications. Using this unique method, a stable, functional and aesthetically pleasing reconstruction can be accomplished.
Adult↗
Total condylar prosthesis placement in knee arthroplasty. Biomechanic analysis of human knee preparations.
Knee replacement using the Total Condylar Prosthesis was carried out on six large cadaveric knees. Tibiofemoral articulation was studied radiographically with the tibial component placed anteriorly as well as posteriorly on the tibial plateau. It is concluded that, in this model, when using the Total Condylar Prosthesis for big-sized knees, a tall, posteriorly placed tibial component gave the best placement of the femoral component and the most central tibio-femoral articulation, entailing optimal distribution of the load on the trabecular bone beneath the tibial component.
Biomechanical Phenomena↗
Long-term followup of uncemented tumor endoprostheses for the lower extremity.
Between 1982 and 1989, 100 primary lower limb reconstructions were done using the Kotz Modular Femur Tibia Reconstruction System after resection of a malignant tumor. In 32 patients a proximal femur prosthesis was implanted, in 40 patients a distal femur prosthesis was implanted, in 19 patients a proximal tibia component was implanted, in four patients a total femur prosthesis was implanted, and in five patients a total knee prosthesis was implanted. The Kaplan-Meier estimate of the overall survival rate of the prostheses was 85% after 3 years, 79% after 5 years, and 71% after 10 years. The most common reason for implant failure was aseptic loosening in 27% of patients (11 patients; range, 10-121 months) after the initial operation. The other reasons for revision surgery were implant fracture (n 5 4) and infection (n 5 4). Early repair of prostheses-related minor complications, such as worn polyethylene bushings, resulted in a statistically significant reduction of implant failure. After a median followup of 127.5 months after the initial surgery, 51 patients had died and eight patients were lost to followup. Forty-one patients were evaluated clinically and radiologically using the Musculoskeletal Tumor Society score and the radiologic implant evaluation system of the International Symposium on Limb Salvage; these 41 patients had a mean of 80% (range, 40%-100%) of the normal functional capability.
Adult↗
The "turn-up" plasty: one solution to a complex problem.
This case study presents a patient with severe osteomyelitis of the femur, which did not respond to vigorous antibiotic therapy. Compromised kidney function, malnutrition, and copious drainage from an open wound led the patient and physician to select a seldom used procedure, the "turn up" plasty to treat the problem. This procedure provides a stump for an above-the-knee prosthesis providing the patient with more optimal function than if the femur and lower leg were amputated. The procedure involves removal of the infected femur, foot amputation, knee disarticulation and turning the lower leg up, using the tibia to support the femoral component of a joint replacement. After several months, the patient is wearing a prosthesis, walking without pain, and satisfied with his decision.
Amputation, Surgical↗
Teicoplanin-containing cement spacers for treatment of experimental Staphylococcus aureus joint prosthesis infection.
Using a rabbit model of methicillin-resistant Staphylococcus aureus knee-prosthesis infection, we studied the efficacy of teicoplanin cement alone or in combination with systemic intramuscular (i.m.) injections of teicoplanin. Seven days after infection, surgical debridement and removal of the infected prostheses were performed, and five rabbits were randomly assigned to one of five different treatment groups: untreated controls, prosthesis replacement by drug-free cement spacer, prosthesis replacement by teicoplanin-loaded cement spacer (1.2 g of teicoplanin/40 g of cement), i.m. injections of teicoplanin (20 mg/kg of body weight, twice a day for 7 days), or systemic antibiotic treatment combined with teicoplanin-loaded spacers. The most effective regimen combined systemic teicoplanin and antibiotic spacers.
Animals↗
The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing.
OBJECTIVE: To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. DESIGN: An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated. BACKGROUND: The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well. METHODS: Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0 degrees and 10 degrees. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees and 5 degrees ) of the femoral component relative to the tibial component. RESULTS: The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial-lateral malalignment in these three prostheses. In anterior-posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93-0. 96 in Genesis and 0.96-1.04 in AMK. In internal-external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses. CONCLUSIONS: This study proposes that contact alignment would affect the contact characteristics, especially in anterior-posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses. RELEVANCE: This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.
Biomechanical Phenomena↗
[Effect of component positioning on patellar problems in total knee replacement].
The alignment and size of the components of a knee-prosthesis is most important for a successful and durable total knee arthroplasty. The effect of positioning the components on the patellafemoral joint is described in detail.
Arthroplasty, Replacement, Knee↗
Oral treatment of Staphylococcus spp. infected orthopaedic implants with fusidic acid or ofloxacin in combination with rifampicin.
Oral therapy of staphylococcal infection of orthopaedic implants with 900 mg/day rifampicin combined with either 1.5 g/day fusidic acid for 5 days followed by 1 g/day thereafter, or 600 mg/day ofloxacin was compared. Patients with an infected hip were treated for 6 months, with removal of any unstable prosthesis after 5 months' treatment and those with an infected knee prosthesis were treated for 9 months, with removal of the prosthesis after 6 months of treatment. Patients with infections of other type of bone implants were treated for 6 months with removal of the implant after 3 months of treatment, if necessary. Cure was defined as the absence of clinical, microbiological and radiological evidence of infection 12 months after completion of treatment. The treatment of 46 of the 52 included in the study was evaluated for safety and that of 42 was assessed for efficacy. Overall treatment was successful for 11 (55%) of 20 patients treated with rifampicin and fusidic acid group and for 11 (50%) of the 22 treated with rifampicin and ofloxacin. Treatment failed in four cases in each treatment group because of persistent infection. One patient given rifampicin and fusidic acid and three patients given rifampicin and ofloxacin failed treatment because of relapse. Superinfection led to failure in the remainder and was due to staphylococci in all but one case in which Acinetobacter calcoaceticus var. anitratus was isolated. There were no side effects related to study treatment. Oral treatment with rifampicin combined with fusidic acid may be a suitable alternative to the combination of rifampicin and ofloxacin for treating implant infections due to Staphylococcus spp. either when the patient is intolerant to quinolones or when the infecting organism is resistant to these drugs.
Administration, Oral↗
Prosthetic fitting immediately after below-knee amputation.
Frequently surgical amputation of a lower extremity is required when gangrene develops as a result of peripheral vascular disease. This is particularly true in geriatric patients. A below-knee amputation, with refinements in the surgical procedure, and immediate rigid-cast prosthetic fitting are strongly advocated by our group. The progress of two patients treated in this manner is described. Preservation of the knee joint improves the amputee's prognosis for ambulation with a below-knee prosthesis. The rigid-cast dressing on the below-knee amputation reduces edema and postoperative pain, is of psychologic value to the patient, and permits him to stand at from one to two days postoperatively.
Aged↗
Dislocation of Insall-Burstein II modified total knee arthroplasty.
Dislocation of total knee arthroplasty is a rare but serious complication. The experience with the Insall-Burstein II modified knee prosthesis, which was designed to address the issue of dislocation, has been favorable. We present a series of 3 dislocations in 1,500 total knee arthroplasties done with this prosthesis, accounting for about 0.2% of cases.
Aged↗
Retropatellar contact characteristics before and after total knee arthroplasty.
PURPOSE: Qualitative analysis of the retropatellar contact characteristics after total knee arthroplasty. MATERIAL AND METHODS: Six cadaveric knees were investigated before and after implantation of a Genesis I knee prosthesis without and with patellar resurfacing in different positions. Joint contact characteristics were evaluated with Fuji Prescale film type 'Super Low' and analyzed qualitatively in nine quadrants. The pressure was determined from a 5-s loading duration in four different knee positions between 45 degrees and 120 degrees of flexion. The femoral component of the prosthesis was implanted in neutral as well as in internal and external rotation. A quadriceps force of 280 N with either a predominant medial or lateral pulling direction was applied. RESULTS: Without prosthesis the largest contact area is between 60 degrees and 90 degrees of flexion. A lateral muscle force direction as well as an external rotation increased the frequency of loading in the medial quadrants. After implantation of the prosthesis the central and superior quadrants were predominantly contacted irrespective of the flexion angle. No marked differences between the flexion angles were found. Implantation of the patellar resurfacing led to contact in the three central quadrants. CONCLUSION: Implantation of the endoprosthesis leads to increased contact in slight and extreme flexion angles. Especially the central areas are increasingly loaded. No predominant influence of the rotation of the femoral component or the direction of the muscle pull was found. An improved distribution of the contact area could not be demonstrated after patellar resurfacing.
Aged↗
Unicompartmental knee arthroplasty. A 4.5-6-year follow-up study with a metal-backed tibial component.
The results in the first 50 patients to receive an improved-design unicompartmental knee prosthesis were reviewed after an average follow-up period of 5.5 years. The prosthesis is composed of a metal-backed polyethylene tibial component and a wide femoral surface replacement that are fixed to bone with acrylic cement. Forty-five patients with 55 unicompartmental knee arthroplasties were available for clinical study. Ninety-two percent of the knees were rated as having a good or excellent result, and 94% had lasting relief of pain. There have been no failures requiring revision. A radiographic review demonstrated that no tibial component was bordered by a complete radiolucent line. There was no subsidence or loosening of either the tibial or femoral components, and there was no instance of local osteolysis. These results, coupled with a 14-year follow-up experience with the original-design unicondylar prosthesis, encourages the authors to remain advocates of this procedure in selected patients with unicompartmental osteoarthritis.
Aged↗
Mechanical evaluation of mobile bearing knees.
To evaluate the mechanical behavior of a new mobile bearing knee prosthesis (MBK, Zimmer, Swindon, United Kingdom), two experimental studies were performed. In the first study, by superimposing a transparent template of the MBK on lateral radiographs taken in 15 normal cadaveric knees at 15 degrees intervals from 0 degree to 120 degrees of flexion, the displacement of the mobile bearing surface in respect to the tibial plateau was measured. By increasing the knee flexion, the mobile bearing surface moved progressively backward from an average value of 1.4 mm at 0 degree to an average value of 7 mm at 120 degrees of flexion. In the second study, by using pressure-sensitive Fujifilm, the contact pressure distribution across the upper and lower bearing surfaces of closely conforming mobile bearing knees was analyzed to determine if small differences in the relative radii of curvature resulted in pressure changes distribution. Five metal cylinders of different radii of curvature were used to reproduce the femoral components. For the femoral plastic bearing surface, the contact pressure distribution was uniform when there was an interference of 0.1 to 0.2 mm. For the plastic tibial plate bearing surface, uniform pressure was achieved for radii that were equal. The results of the first study indicate that the MBK prosthesis, retaining the posterior cruciate ligament and having no preferred axis of movement on its own, can follow the pattern of movement that the retained ligaments dictate. The second study confirms that between closely conforming surfaces, the pressure distribution is uniform, and small differences in the relative radii of curvature affect the pressure distribution.
Cadaver↗
[The GSB knee joint: reoperation and infections].
The GSB-III knee prosthesis is one of the semi-constrained types and consequently ranks between the non-constrained condylar prostheses and the fully constrained hinges. Its kinematics can be classified as "physiological" in the sagittal plane as far as the relationship between femur and tibia in the various degrees of flexion is concerned, which is a replica of a normal knee joint. The high average range of postoperative mobility as well as the extremely low aseptic loosening rate after 10 years prove the truth of this statement. A simple operative technique requiring a few special instruments allows even the less experienced knee surgeon to be successful and to obtain good results in cases with severe deformity and poor bone quality. The survival curves of the GSB-III prosthesis (n = 638) show a cummulative success rate of over 90% after 10 years. Looking separately at cases complaining of more or less severe pain, we frequently find underlying patellar problems, the main cause for revisional surgery. This problem is not specific for our prosthesis, but must be considered a so far unsolved worldwide problem. Infections are another relatively frequent cause for revisions. Disturbed wound healing, arterial insufficiency and malignant rheumatoid arthritis are the outstanding risk factors. For a reliable comparison of the different knee prostheses we ought to have a globally accepted evaluation system, which unfortunately still does not exist.
Adolescent↗
Ankle-knee synchronous in a new endoskeletal above-knee prosthetic mechanism: a preliminary report.
A new above-knee prosthetic mechanism with synchronous motions of the knee and ankle has been designed based on kinematic principles. Knee flexion is synchronized with ankle dorsiflexion by a synchronizer rod and lever. Unlike other above-knee units, the knee joint is aligned about one inch in front of a line between the hip and the ankle joints, which appears to decrease the energy requirements of gait. The swing-phase control system provides constant friction during ordinary cadence and variable friction during rapid swinging of the leg. The addition of a quadrilateral socket, a modified SACH foot and a cosmetic foam plastic cover provides the complete endoskeletal above-knee prosthesis. The resulting gait has been found to be faster, easier and more natural, and the three optional knee settings serve the needs of different amputees and activities.
Ankle Joint↗