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At least 307 records · Page 17Linked to original sources
PubMed1993

Noncemented, porous ingrowth knee prosthesis: the 3- to 8-year results.

OBJECTIVE: To determine the principal long-term problems encountered in noncemented total knee replacement. DESIGN: A cohort of 252 consecutive cases of total knee replacement with no exclusions. Follow-up ranged from 3 to 8 years. SETTING: A university-affiliated institution specializing in orthopedic surgery. PARTICIPANTS: All 252 patients had arthritis of the knee, mainly osteoarthritis. All agreed preoperatively to prolonged postoperative follow-up. INTERVENTION: Noncemented total knee replacement with the Tricon M prosthesis, which has a metal-backed patella. MAIN OUTCOME MEASURES: The Hospital for Special Surgery rating system for clinical results and the radiologic results, including reasons for revision surgery. RESULTS: Thirty-five prostheses were revised: 11 prostheses because of patellar wear only; in 13 prostheses the tibial component (mainly a 6-mm unit) and patella were revised because of wear; 6 prostheses were revised for sepsis, 4 for reflex sympathetic dystrophy and 1 only for sinkage of the tibial component. Of the remaining 217 prostheses, 88% scored good or excellent, 6% fair and 6% poor. CONCLUSIONS: The single most common cause of failure was polyethylene wear. This was associated with the metal backing of the patella and the use of thin, polyethylene tibial components.

Adult↗
PubMed1993

[Single-compartment "Lotus" type knee prosthesis in the treatment of lateralized gonarthrosis: results in 135 cases with a mean follow-up of 4.6 years].

Controversy exists on the indications and results of unicompartmental arthroplasty in the treatment of unicompartmental knee arthritis. This led us to study 135 Lotus prostheses implanted from December 1974 to February 1990. The follow-up lower than 1 year for 14 knees (11 were lost to follow-up, 3 were reoperated). One hundred and twenty-one knees were clinically evaluated with an average follow-up of 4 years and 6 months using both the GUEPAR and the Knee society grading systems. 71.9 per cent of the knees were rated good, 28.1 per cent were rated poor (19 per cent were revised). This important rate of poor results was due to poor technique (11 knees) and to poor indications (7 knees). Polyethylene wear, and radiolucent line especially when it was evolutive were significantly correlated to failures and poor results. Failures were seldom unifactorial but often multifactorial. Over or undercorrection of coronal deformity, absence or lengthening of the anterior cruciate ligament were the failure factors most often found. Decrease of good results with time, and polyethylene wear of unicompartmental arthroplasties are factors which lead us to carefully consider osteotomy for patients under 65 years. The failure rate may decrease with good indications and a better technique allowing unicompartmental arthroplasty to be a good choice for unicompartmental arthritis.

Adult↗
PubMed1995

[Total knee prosthesis. Clinical and numerical study of micromovements of the tibial implant].

INTRODUCTION: The importance of the micromovements in the mechanism of aseptic loosening is clinically difficult to evaluate. To complete the analysis of a series of total knee arthroplasties (TKA), we used a tridimensional numerical model to study the micromovements of the tibial implant. MATERIAL AND METHODS: Fifty one patients (with 57 cemented Porous Coated Anatomic TKAs) were reviewed (mean follow-up 4.5 year). Radiolucency at the tibial bone-cement interface was sought on the AP radiographs and divided in 7 areas. The distribution of the radiolucency was then correlated with the axis of the lower limb as measured on the orthoradiograms. The tridimensional numerical model is based on the finite element method. It allowed the measurement of the cemented prosthetic tibial implant's displacements and the micromovements generated at bone-ciment interface. A total load (2000 Newton) was applied at first vertically and asymetrically on the tibial plateau, thereby simulating an axial deviation of the lower limbs. The vector's posterior inclination then permitted the addition of a tangential component to the axial load. This type of effort is generated by complex biomechanical phenomena such as knee flexion. RESULTS: 81 per cent of the 57 knees had a radiolucent line of at least 1 mm, at one or more of the tibial cement-epiphysis jonctional areas. The distribution of these lucent lines showed that they came out more frequently at the periphery of the implant. The lucent lines appeared most often under the unloaded margin of the tibial plateau, when axial deviation of lower limbs was present. Numerical simulations showed that asymetrical loading on the tibial plateau induced a subsidence of the loaded margin (0-100 microns) and lifting off at the opposite border (0-70 microns). The postero-anterior tangential component induced an anterior displacement of the tibial implant (160-220 microns), and horizontal micromovements with non homogenous distribution at the bone-ciment interface (28-54 microns). DISCUSSION: Comparison of clinical and numerical results showed a relation between the development of radiolucent lines and the unloading of the tibial implant's margin. The deleterious effect of lower limbs' axial deviation is thereby proven. The irregular distribution of lucent lines under the tibial plateau was similar of the micromovements' repartition at the bone-cement interface when tangential forces were present. A causative relation between the two phenomenaes could not however be established. Numerical simulation is a truly useful method of study; it permits to calculate micromovements which are relative, non homogenous and of very low amplitude. However, comparative clinical studies remain as essential to ensure the credibility of results.

Aged↗
PubMed2006

A third-generation, posterior-stabilized knee prosthesis: early results after follow-up of 2 to 6 years.

Two hundred seventy-nine primary total knee arthroplasties were performed with a modular, cemented, third-generation, posterior-stabilized prosthesis. At mean follow-up of 48 months (range, 24-72 months), the outcomes of 238 knees (85%) were evaluated with the Knee Society's Knee and Functional Scoring Systems and Roentgenographic Scoring System. The mean preoperative Knee Society Knee Score was 48 points compared with 96 points at latest follow-up. There were no cases of patellar clunk, symptomatic patellar maltracking, or posterior dislocation. There was no radiographic evidence of loosening or osteolysis, and no revisions were performed or recommended for loosening, osteolysis, instability, or polyethylene wear. Three patients developed late infections. These early results support the ongoing use of this design; however, long-term studies will be required.

Adult↗
PubMed1993

[Reoperation after failure of unicompartmental knee prosthesis. Therapeutic strategy and results based on 40 cases].

Forty revisions for failure of unicompartmental knee prostheses were assessed. Twenty-eight women and twelve men (mean age: 67 years) were reoperated. Failure of an medial single-compartment prosthesis was involved in 35 cases, of a lateral prosthesis in 5 cases. The initial prostheses had been cemented in 19 cases and uncemented in 21 cases. Preoperative functional conditions were assessed by Hungerford's functional score and a 200-points score. The radiological study before revision showed 35 cases of varus distortion; in 12 of these, the varus distortion exceeded 10 degrees. Rather than studying the causes for failure of the single-compartment prosthesis, it seemed more useful to try to define the adequate reoperation procedure strategy and analyze its results. Our procedure aimed at solving the following difficulties: surgical approach: the same incision as in the initial operation was performed, the primary prosthesis was removed and a two-stage treatment was justified in cases of infection, metallosis involved complete removal of debris, the problem of bone-recutting and, chiefly, the problem of residual bone defect requiring bone-graft. Bone-recutting was performed with the tibial and femoral elements of the primary prosthesis still in place and using the ancillary equipment of the new prosthesis. Bone defects involved the femur as often (14 cases) as the tibia (12 cases); tibial bone defects occurred more frequently with cemented prostheses (9 cases) than with uncemented prostheses (3 cases). Femoral graft being relatively easier to perform one of the two major difficulties in our strategy was the achievement of a tibial graft.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1981

The gastrocnemius myocutaneous flap used as a over for the exposed knee prosthesis.

Exposure of the prosthesis is one of the problems encountered after arthroplasty of the knee. Eight patients with nine exposed prostheses have been treated by using a gastrocnemius myocutaneous flap to provide cover. This preserved the prosthesis and closed the joint in six of the eight patients.l The factors leading to breakdown of the wound are discussed and the anatomy of the gastrocnemius myocutaneous flap and the operative procedure are described.

Aged↗