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PubMed1991

[Distribution of transverse dimensions of the patella in the adult population. Relation to the development of the patellar component in knee joint prosthesis].

The development and manufacture of the patellar component was associated with a more detailed osteometric investigation of the patella and evaluation of its range of sizes in our population. Evaluation of data 1042 probands (477 women, 565 men) proved: a) there are no significant lateral differences of transversal dimensions of the patella and femoral condyles; b) The mutual relationship of the above mentioned dimensions does not correlate, and thus no conclusions can be drawn from the transversal breadth of the condyles on the dimensions of the patella; c) The range of patellar diameters in the population is very wide, and to meet demands, it will be necessary to manufacture patellar components in cca five sizes.

Adolescent↗

PubMed2002

Results of periprosthetic hip and knee infections caused by resistant bacteria.

Seventy patients with deep periprosthetic hip or knee infections were treated between May 1997 and March 2001. Thirty-five patients had periprosthetic infections of their total hip arthroplasties and 35 patients had periprosthetic infections of their total knee arthroplasties. The patients were subdivided into two subgroups: patients who had infections with Staphylococcal bacterial strains that were sensitive to methicillin and patients who had infections with bacteria that were resistant to methicillin (methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus epidermidis). Treatment was considered successful if the patient was able to retain his or her hip or knee prosthesis either as a result of irrigation and debridement procedures alone or after excision of the infected total hip or knee prosthesis followed by successful reimplantation. Treatment was considered a failure if the patient eventually required arthrodesis, amputation, or was left with a permanent excision arthroplasty. Hip replacements that were infected with antibiotic-sensitive bacteria were treated successfully in 81% of cases. In contrast, hip replacements infected with resistant organisms were treated successfully in only 48% of cases. Similarly, knee replacements infected with sensitive organisms had a success rate of 89%, compared with only 18% of the total knee replacements that were infected with resistant bacterial strains.

Adult↗

PubMed1992

[Delayed autologous transfusion in prosthetic surgery of the hip and knee].

Blood sparing methods used during hip or knee prosthesis implantation or change in 360 patients during the years 1990-1992 were evaluated. For delayed transfusion of autologous blood the main counter-indication was unstable cardiovascular condition. Such cases being excluded, the method was used in 64.2% of all cases. No homologous blood was needed in 68.9% of patients. This result was obtained in 55% of the cases by delayed transfusion of autologous blood and in 13.9% by peroperative normovolaemic haemodilution.

Adult↗

PubMed1986

Limb salvage and prosthetic joint reconstruction for low-grade and selected high-grade sarcomas of bone after wide resection and replacement by autoclaved [corrected] autogeneic grafts.

Wide resection is an acceptable alternative to amputation for the management of primary sarcomas of the long bones or pelvis. The resected bone can be debrided of gross tumor tissue, autoclaved, and then replaced over intramedullary fixation to reconstruct the limb anatomically. The procedure can be combined with prosthetic reconstruction of adjacent joints with sufficient strength to allow early unprotected weight-bearing. Resection and replacement for 28 low-grade (G1) and 14 selected high-grade (G2) sarcomas were performed in 42 patients. The hemipelvis was resected and replaced four times, the proximal or distal femur 28 times, the proximal or distal tibia eight times, and the proximal humerus two times. Replacement of an adjacent joint, most commonly using a long-stemmed hip or knee prosthesis, was accomplished in 33 patients. All patients had been followed for a minimum of two years, nine months after treatment. The mean follow-up period is four years, ten months. Six individuals, all with high-grade sarcomas, developed tumor-related complications. Two evidenced a local recurrence of tumor, and four developed distant metastases. None of the patients with low-grade sarcomas developed a recurrence or metastases. Fifteen patients suffered complications unrelated to tumor control; 13 required reoperation, including two who required amputations for persistent pseudoarthrosis and graft infection, respectively. There was one other infection, successfully eradicated by drainage followed by local and systemic antibiotics. Due to mechanical failure or loosening, six patients were treated by successful revision of their joint arthroplasties. Two years after initial surgery, five patients had failures of union at the graft-host junction. Four healed after cancellous grafting and one was revised to a custom prosthesis. There were no late fatigue fractures of the grafts. The technique does not compromise the margins for adequate tumor resection. It preserves a graft strong enough to support a joint arthroplasty and to allow early weight-bearing with a low risk of pseudarthrosis or late fatigue fracture.

Adolescent↗

PubMed2001

Ten- to 14-year clinical followup of the cementless Natural Knee system.

Of 300 consecutive knees (238 patients) that had undergone arthroplasty with the cementless Natural Knee prosthesis from 1985 to 1989, 176 knees (141 patients) were available for followup at an average of 12 +/- 1 years after the operation. Knee function was improved significantly. Modified Hospital for Special Surgery knee scores improved from 59.1 +/- 13.2 points preoperatively to 97.8 +/- 4.7 points at last followup. At last followup, knee range of motion averaged 0 degrees +/- 2 degrees to 120 degrees +/- 10 degrees. Implant survival was 93.4% (including infection and simple polyethylene exchanges) and 95.1% (excluding infection and simple polyethylene exchanges) at 10 years when applying the Kaplan-Meier survival analysis, using loose components, revision, or both as failure criteria. Besides the three revisions for infection, only two femoral and one tibial component required revision. The patellar component survivorship at 10 years was 95.1%. All patellar revisions were attributed to edge wear. Subsequent operative and design changes, including patellar component medialization and countersinking, have decreased the incidence of patellar revision. The long-term results of this cementless knee system compare favorably with those of cemented systems. The Natural Knee design has provided excellent and predictable long-term clinical results in the current series of active patients.

Aged↗

PubMed2002

The effect of malalignment on stresses in polyethylene component of total knee prostheses--a finite element analysis.

OBJECTIVE: To investigate the effects of malalignment on stresses in tibial polyethylene component of total knee prostheses. DESIGN: A three-dimensional finite element analysis was used to calculate the contact stress and von Mises stress in the tibial polyethylene component subjected to a compressive load, and the malalignment situations were simulated. BACKGROUND: Many biomechanical studies to investigate the stresses in tibial polyethylene component were assumed at the ideal contact alignment. The effect of malalignment on stresses in tibial polyethylene component was not investigated extensively. METHODS: Three-dimensional finite element models of the tibiofemoral joint of knee prostheses for three different designs were constructed. Three malalignment conditions including the medial translation (0.25, 0.5 and 1.0 mm), internal rotation (1 degree, 3 degree and 5 degree), and varus tilt (1 degree, 3 degree and 5 degree) of the femoral component relative to the tibial component were simulated. A compression load of 3000 N was applied to the tibiofemoral joint at 0 degree of flexion. The maximum contact stress and von Mises stress in the tibial component were compared to investigate the effects of malalignment. RESULTS: In comparing with the neutral position, the greatest increase of maximum contact stress were 67.6%, 14.3% and 145.9% and the greatest increase of maximum von Mises stress were 92.5%, 22.7% and 120.6% in maltranslation, internal rotation and varus tilt simulations, respectively. CONCLUSION: The greatest increase of contact stress and von Mises stress was occurred in the high conformity flat-on-flat design of knee prosthesis under the severest malalignment condition. The high conformity curve-on-curve design of knee prosthesis has the minimal risk of polyethylene wear under the malalignment conditions. RELEVANCE: This study revealed the importance of malalignment effect on stresses in tibial polyethylene component. Polyethylene wear in surface replacement total knees will be minimal when a high conformity curve-on-curve knee design is used and the rotational line between the femoral and tibial components has the least effect on polyethylene wear but varus/valgus malalignment, even with the best designed prosthesis will still accelerate wear.

Bone Malalignment↗

PubMed2002

[Influence of the height of the joint space on the three-dimensional kinetics of total knee prostheses and behavior of the lateral ligaments: an in vitro study].

PURPOSE OF THE STUDY: The level of the joint space can be modified after implantation of a total knee prosthesis. Likewise, ligament balance is a cardinal point of the surgical technique. The purpose of this in vitro work was to study the influence of the position of the distal tibiofemoral joint space after implantation of a total knee prosthesis on the three-dimensional kinetics of the knee joint and on the behavior of the lateral ligaments. MATERIAL AND METHOD: Total knee arthroplasty (TKA) with a posterior stabilized prosthesis was performed on seven fresh-frozen cadaver specimens. A specially-designed experimental device was used to achieve continuous knee motion simulating hip flexion from a vertical position. The Vicon optoelectronic system was used to record the femorotibial and femoropatellar kinematics in three dimensions. Two electronic goniometers were positioned on the insertions of the lateral ligaments to measure ligament displacements during knee movements. Five configurations were recorded on each knee: healthy knee, same knee after TKA, and 2-mm and 4-mm upward displacement of the prosthetic distal tibiofemoral joint space. Ligament balance at extension was preserved in all configurations. The kinematic curves obtained were compared with the coefficient of multiple correlation. RESULTS: Changing the position of the joint space had a significant effect on the kinematics of the patella (rotation and abduction-rotation) but did not have a significant effect on the femorotibial kinematics. Variations in the length of the lateral ligaments were of small amplitude. Lowering the joint space led to laxity at flexion. Raising the joint space tightened the ligaments at flexion. DISCUSSION: These results confirm our clinical impression when the level of the distal femur cut is set to achieve tension on the ligaments at knee extension. If the joint space is lowered, i.e. with a more sparing distal femur cut, the prosthesis takes up less space during flexion, leading to laxity at flexion. If the joint space is raised, i.e. with an excessive distal femur cut, the prosthesis takes up more space during flexion, tightening the lateral ligaments. CONCLUSION: The position of the joint space must be rigorously reproduced during TKA not only to maintain correct femorotibial kinematics, but most importantly to preserve patellar kinematics and proper behavior of the lateral ligaments. Ideally, the height of the joint space should be restored first, followed by control of the ligament balance. An over- or undercut of the femur can lead to defective femoropatellar kinematics and ligament tension at flexion despite good ligament balance at extension. In addition, ligament balance should not be achieved by displacing the tibial cut or by modifying the thickness of the tibial component, which would have an effect not only at extension but also at flexion.

Anthropometry↗

PubMed1995

Fabellar impingement after total knee replacement--a case report.

An unusual postoperative knee pain caused by fabellar impingement after total knee replacement is described. A 68-year-old woman with knee arthrosis had large fabellae in both knees. She had total knee replacements of both knees. One knee developed fabellar impingement to the knee prosthesis, while the other knee was free of symptoms due to simultaneous fabellectomy during knee replacement. At 3-month postoperative follow-up, pain and local tenderness at posterolateral aspect of the left knee was noted during flexion up to 90 degrees. Physical examination revealed a tender fabella on the posterolateral part of the left knee. The lateral radiograph of the knee revealed a large fabella impinging on the prosthesis. The symptoms and signs were alleviated after surgical excision of the fabella. Careful evaluation of the preoperative lateral radiograph of the knee is necessary to detect a large fabella. If it is present and larger than 1 cm, excision during knee replacement is recommended.

Aged↗

PubMed2003

No augmentation of morselized and impacted bone graft by OP-1 in a weight-bearing model.

INTRODUCTION: Impacted morselized bone allograft is thought to be remodeled to a great extent. We have previously shown that load-bearing increases the remodeling of impacted morselized bone allografts in a rabbit knee prosthesis model. Bone Morphogenic Proteins (BMPs) also stimulate bone formation and bone allograft remodeling. In this study, our aim was to determine whether it was possible to increase further the remodeling of impacted morselized bone allografts by combining load-bearing with a BMP. EXPERIMENT: A solution of Osteogenic Protein-1 (OP-1, also called BMP-7) was added to freeze-dried bone allograft chips before impaction grafting in our rabbit knee prosthesis model. 23 skeletally mature rabbits received an uncemented tibial knee prosthetic component inserted into a bed of impacted morselized bone allograft. 12 rabbits were given OP-1-treated allograft (50 microg OP-1 per gram allograft), and 11 rabbits vehicle-treated allograft. Each rabbit received mean 0.53 g graft. The rabbits were killed after 3 or 6 weeks and the grafted region was examined by histomorphometric assessment of the volume fraction of newly formed bone and remaining graft. RESULTS AND INTERPRETATION: We found that OP-1 did not increase the bone density (graft plus new bone) to any substantial extent. However, we can not exclude that this might be due to a carrier problem, since the OP-1 was added as a solution directly to the dry graft.

Animals↗

PubMed2004

Rotationplasty about the knee: surgical technique and anatomical considerations.

Rotationplasty is an intercalary resection of a bone segment with subsequent reconstruction of the lower limb by rotating it through an arc of 180 degrees. After rotation, the rotated ankle functions as a knee joint, thereby powering a custom-made below-knee prosthesis. Rotationplasty is a satisfactory treatment option in selected patients. A prerequisite for this type of surgery is an intact sciatic nerve. Rotationplasty is indicated for skeletally immature patients with a tumoral lesion about the knee (<8-10 years of age), for older patients with large lesions that are not candidates for limb salvage as an alternative to above-knee amputation, and as a salvage procedure for chronically infected prosthetic implants. Preoperative planning includes the prediction of the exact remaining bone growth, because the ipsilateral distal tibial epiphysis will not completely substitute for the growth deficit resulting from the resected distal femoral and proximal tibial epiphyses. Therefore, minimal over length of the ankle of the operated leg is retained. Technical details of the surgery are described with particular emphasis on anatomical considerations. It provides a durable and biologic reconstruction and allows patients to become good functional below-knee prosthesis users and allows participation in recreational activities and sports.

Arthroplasty, Replacement, Knee↗

PubMed2005

Ligament strains predict knee motion after total joint replacement: a kinematic analysis of the sigma knee.

A passive forward kinematics knee model was used to predict knee motion of a total joint replacement. Given ajoint angle, maps of articular surfaces, and patient-specific ligament properties, this model predicted femorotibial contact locations based on the principle of ligament-strain minimization. The model was validated by physical experiments on a commonly implanted knee prosthesis, showing excellent correspondence between the model and actual physical motion. Results suggest that the knee prosthesis studied required an intact posterior cruciate ligament to induce the desirable roll-back motion, and that a single-bundle model of major knee ligaments generated kinematics similar to that of a multibundle ligament model. Implications are that a passive model may predict knee kinematics of a given patient, so it may be possible to optimize the implantation of a prosthesis intraoperatively.

Arthroplasty, Replacement, Knee↗

PubMed1988

Prediction of fatigue failure of a total knee replacement tibial plateau using finite element analysis.

Recent reports of total knee prosthesis fractures have raised concerns over the long-term structural integrity of metal-backed tibial components. Both the development of a fibrous tissue membrane under the tibial plateau of a total knee prosthesis and loading conditions may seriously alter the fatigue life of the metal tibial tray. The effects of the cement and fibrous tissue at the bone-prosthesis interface were studied. Using the method of three-dimensional finite element analysis, peak loads of normal gait were simulated at several locations on the plateau of a generic, single-stemmed, porous-coated, CoCrMo tibial component model, providing information on the effect of abnormal loading patterns. According to the analysis, stresses below the material endurance limit are predicted throughout the prosthesis prior to the development of the fibrous membrane. However, stresses exceeding the yield strength of the material are predicted in a prosthesis that is supported by a fully developed 1 mm membrane, meaning that it has a markedly increased risk of low-cycle fatigue failure. Lateral displacement of the loading is detrimental to prosthesis life because maximum stress increases 100% while posterior displacement of the loading increases maximum stress by only 30%. Anterior loading creates stresses similar to those created by central loading. Because of their susceptibility to low-cycle fatigue failure, simple, single-stemmed prostheses are not recommended in cases of questionable bone stock unless modified. Several design alternatives are proposed.

Bone Cements↗

PubMed2002

A mechanical comparison of 2 posterior-stabilizing designs: Insall/Burstein 2 knee and Bisurface knee.

A posterior-stabilizing knee prosthesis, called the Bisurface knee (Kyocera Corp, Kyoto, Japan), with a ball-and-socket joint installed in the midposterior portion of the tibiofemoral joint, has been developed to satisfy 2 conflicting demands in knee joint design: kinematics and wear resistance. To confirm if the prosthesis has achieved its design objectives, a contact area and stress study was done throughout the range of motion and compared with results obtained for the Insall-Burstein 2 knee. The posterior-stabilizing ability of the ball-and-socket joint also was assessed. This study showed that the ball-and-socket joint could provide sufficient posterior stability, earlier start of flexion, and lower contact stress in the tibial polyethylene insert in flexion. The design of the Bisurface knee could provide a good balance between kinematics, stability, and wear resistance.

Arthroplasty, Replacement, Knee↗

PubMed1980

[Experiences gained with knee endoprostheses (author's transl)].

Authors report on their experiments and observations with knee endoprostheses. On reason of the high price of imported prostheses the home production of implantates is urged. They reported in a preliminary paper in 1977 on the insertion of the first knee prosthesis made in Hungary. Since this time in 36 instances have been inserted without complication their titanium-polyamid and stainless steel-polyamid sledge type prostheses (a total of 42 pairs of 32 patients). After 2 years follow up the results can be classified as "very good". A new improved model of knee prosthesis is under elaboration.

Arthritis, Rheumatoid↗

PubMedDate not supplied

[Kinematics of various joint mechanisms for the prosthetic substitution of the knee joint following knee exarticulation].

In the past, long amputation stumps of the thigh after knee disarticulation were difficult to fit with a knee prosthesis. Apart from other difficulties, one essential problem was caused by the fact that in preservation of the femoral length there was little or even no space to assemble a knee prosthesis at the level of the axis of the natural knee joint, that is to say at a position somewhere within the femoral condyles. In the meantime the number of knee disarticulations has increased and thus substituted the conventional above knee amputation. Consequently some new, partly polycentric knee joint mechanisms have been designed for the prosthetic fitting of knee disarticulation stumps as well as for long amputation stumps of the thigh. These mechanisms try to cope with the space problem in different ways and, moreover, some of them can also produce a moving centre of rotation at joint flexion similar to the natural knee joint. The motion pattern in current knee joint mechanisms is investigated by graphical construction of their centrodes and it is compared to the motion pattern of the natural knee joint.

Artificial Limbs↗

PubMed1999

Nonunion of tibial stress fractures in patients with deformed arthritic knees. Treatment using modular total knee arthroplasty.

In two years we treated four women with ununited stress fractures of their proximal tibial diaphyses. They all had arthritis and valgus deformity. The stress fractures had been treated elsewhere by non-operative means in three patients and by open reduction and internal fixation in one, but had failed to unite. After treatment with a modular total knee prosthesis with a long tibial stem extension, all the fractures united. A modular total knee prosthesis is suitable for the rare and difficult problem of ununited tibial stress fractures in patients with deformed arthritic knees since it corrects the deformity and the adverse biomechanics at the fracture site, stabilises the fracture and treats the arthritis.

Aged↗

PubMed1985

Unrecognized staphylococcal pyarthrosis with rheumatoid arthritis.

Four patients whose rheumatoid arthritis (RA) was complicated by staphylococcal arthritis were identified. All patients had active, long-standing disease with destructive changes. Affected joints included hip (two patients), knee (one patient), and shoulder (one patient). Pain and loss of motion in the affected joint were prominent, but toxic features of pyogenic infections--hectic fever, chills, sweats, local warmth, or erythema--were conspicuously absent. Two patients had moderate fever and three patients had mild leukocytosis. No patient was leukopenic. When present, fever was attributed to infected decubiti or urinary tract infection and treated with antibiotics. Therapy with corticosteroids and nonsteroidal antiinflammatory drugs (NSAIDs) probably masked symptoms and delayed the correct diagnosis. Purulent synovial effusions were discovered serendipitously--during arthrography (knee), attempted Girdlestone procedure (hip), and aspiration prior to steroid injection (shoulder). Sepsis was included in the preoperative diagnoses only once (hip). Prior instrumentation (aspiration or injection) of the affected joint was not a feature in any patients, although one patient had undergone insertion of a knee prosthesis one year prior to sepsis. Infectious organisms were Staphylococcus aureus in three patients and Staphylococcus epidermidis in one. Severe sequelae ensued in three of four patients: death from recurrent sepsis (one patient), loss of prosthesis leading to knee arthrodesis (one patient), and protracted sepsis with additional pyarthrosis (one patient). The only patient to regain preseptic joint function (shoulder) had not been on long-standing corticosteroids. Pyarthrosis must be considered in RA patients with unusually painful or stiff joints even in the absence of toxic symptoms.

Adult↗

PubMed2004

Promoting quality through surveillance of surgical site infections: five prevention success stories.

BACKGROUND: Public reports of successful quality improvement efforts are useful, but seldom available. We present 5 successful efforts to prevent surgical site infections (SSIs) with the use of prospectively collected surveillance data. METHODS: Before-and-after intervention studies were conducted in 5 acute care public hospitals in the national surveillance network for SSI in The Netherlands from 1992 to 2000. Patients undergoing surgery for total hip prosthesis (3 hospitals), knee prosthesis (2 hospitals), prosthesis of the femur head (1 hospital), or appendectomy (1 hospital) were included. Included were 1066 patients before intervention, and 1269 patients after intervention. Multidisciplinary evaluation of infection control policy led to subsequent changes of infection control measures, mainly involving the discipline of staff and organization of perioperative infection prevention procedures. RESULTS: All 5 hospitals drastically reduced their SSI rates to the national average or below. Absolute declines ranged from 2.1% to 13.9%, but not all reductions were statistically significantly different from 0%. CONCLUSION: Surveillance results provide a basis for improvement of infection prevention.

Bacterial Infections↗