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W Norman Scott

Publications and source records attributed to W Norman Scott.

18 recordsLinked to original sources
PubMed2006

Component asymmetry in simultaneous bilateral total knee arthroplasty.

Component size asymmetry and knee scores were determined in a review of 253 patients undergoing simultaneous or same-day, bilateral total knee arthroplasty (TKA). Asymmetry in component sizes was found in 22 (8.7%) pairs of femoral components, 17 (6.7%) pairs of tibial components, and 13 (5.1%) pairs of patellar components. Asymmetric and symmetric total knee arthroplasties were seen equally in men and women, and there was no statistical difference in knee scores and range of motion between patients with symmetric or asymmetric arthroplasties. Asymmetry rates for anterior referenced femoral components were significantly higher than posterior referenced components, an unexpected finding of unknown significance. Awareness of the incidence of component asymmetry and the practice of independent sizing of each knee during bilateral TKA is important to continue the success of bilateral TKA in a growing patient population.

Adult↗
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↗
PubMed2006

Blood loss management in high-risk patients undergoing total knee arthroplasty: a comparison of two techniques.

Although it is well known that patients with preoperative hemoglobin levels <13.0 g/dL are at a higher risk for requiring postoperative transfusions, the ideal blood management strategy for this group of patients remains unclear. This study compared preoperative autologous donation with preoperative administration of epoetin alfa as a method to maximize perioperative hemoglobin levels and minimize blood transfusions in these high-risk patients undergoing total knee arthroplasty (TKA). Results show that both preoperative autologous donation and epoetin alfa were successful in decreasing the need for allogeneic blood transfusions following TKA in high-risk patients. Epoetin alfa was more effective in maximizing perioperative hemoglobin levels.

Adult↗
PubMed2006

Use of multi-detector computed tomography for the detection of periprosthetic osteolysis in total knee arthroplasty.

This study determined the accuracy of plain radiography in detecting osteolytic lesions around total knee prostheses compared to multi-detector computed tomography (CT). Thirty-one patients diagnosed with periprosthetic osteolysis by multi-detector CT after total knee arthroplasty (TKA) were studied. Computed tomography for each patient was retrospectively reviewed in a blinded fashion. The plain radiographs for each patient that had been obtained prior to CT were reviewed in the same manner. The results of the CT were compared with the results of the radiographs. The number, size, and location of the lesions were compared. The multi-detector CT detected 48 lesions in 31 knees: 40 tibial lesions, 4 femoral lesions, and 4 patellar lesions. Radiographic diagnosis was made in 6 of the 40 tibial lesions, 2 of the 4 femoral lesions, and 0 of the 4 patellar lesions. Plain radiographs are inadequate for evaluating periprosthetic osteolysis in TKA with only 8 (17%) of 48 lesions detected by multi-detector CT visible on the standard radiographs. Multi-detector CT provides the surgeon with a diagnostic and preoperative planning tool when osteolysis is suspected.

Aged↗
PubMed2005

Evaluation of the anterior cruciate ligament integrity and degenerative arthritic patterns in patients undergoing total knee arthroplasty.

We prospectively reviewed 107 consecutive primary total knee arthroplasties performed over a 1-year period. Intraoperatively, the integrity of the anterior cruciate ligament (ACL), the characteristics of the intercondylar notch, and the patterns of cartilage wear were evaluated. The ACL was found to be deficient in 41 knees (39%) at the time of surgery. The ACL-deficient knee had significantly narrower intercondylar notch widths compared with knees with an intact ACL (average, 9.75 vs 16 mm, P < .01). Furthermore, patients with ACL deficiency were found to have a higher percentage of Outerbridge grade IV changes at the lateral femoral condyle, lateral tibial plateau, and patellar surfaces when compared to the ACL-intact group. An intact ACL appeared to be protective against severe patellar degeneration. In conclusion, intercondylar notch narrowing from the arthritic process can lead to attrition and rupture of the ACL. An ACL deficiency appears to be associated increased wear of the lateral femorotibial and patellofemoral joints.

Adult↗
PubMed2005

Clinical results in valgus total knee arthroplasty with the "pie crust" technique of lateral soft tissue releases.

Numerous methods for creating symmetric flexion and extension gaps during knee arthroplasty in valgus knees have been proposed, and no consensus exists about the optimal technique. The "pie crust" technique for lateral soft tissue releases has been used extensively, yet few clinical results have been published. In this study, the clinical outcomes of 24 consecutive knees in 24 patients in whom this method was used in conjunction with a cemented posterior-stabilized prosthesis were evaluated. At a mean of 54 months' (range 24-69 months) follow-up, the knees were performing well with a mean Knee Society score of 97 (range 87-100) and mean range of motion of 121 degrees (range 100 degrees -145 degrees). Importantly, there were no clinical failures or cases of postoperative instability and no cases of radiographic loosening or wear.

Adult↗
PubMed2005

In vivo kinematic evaluation and design considerations related to high flexion in total knee arthroplasty.

In designing a posterior-stabilized total knee arthroplasty (TKA) it is preferable that when the cam engages the tibial spine the contact point of the cam move down the tibial spine. This provides greater stability in flexion by creating a greater jump distance and reduces the stress on the tibial spine. In order to eliminate edge loading of the femoral component on the posterior tibial articular surface, the posterior femoral condyles need to be extended. This provides an ideal femoral contact with the tibial articular surface during high flexion angles. To reduce extensor mechanism impingement in deep flexion, the anterior margin of the tibial articular component should be recessed. This provides clearance for the patella and patella tendon. An in vivo kinematic analysis that determined three dimensional motions of the femorotibial joint was performed during a deep knee bend using fluoroscopy for 20 subjects having a TKA designed for deep flexion. The average weight-bearing range-of-motion was 125 degrees . On average, TKA subjects experienced 4.9 degrees of normal axial rotation and all subjects experienced at least -4.4 mm of posterior femoral rollback. It is assumed that femorotibial kinematics can play a major role in patellofemoral kinematics. In this study, subjects implanted with a high-flexion TKA design experienced kinematic patterns that were similar to the normal knee. It can be hypothesized that forces acting on the patella were not substantially increased for TKA subjects compared with the normal subjects.

Arthroplasty, Replacement, Knee↗
PubMed2005

Blood loss and transfusion rates in bilateral total knee arthroplasty.

From 1994 to 1998, we performed 170 bilateral total knee arthroplasties (TKAs) with cemented, posterior cruciate-substituting prostheses. Blood management included preoperative autologous donation, symptom-based transfusion, and autoreinfusion devices. Perioperative allogeneic transfusion rates for patients who donated 0, 1, 2, 3, or 4 units of blood were 40.00%, 0.00%, 3.70%, 0.00%, and 3.23%, respectively. Preoperative autologous donation >2 units also resulted in lower preoperative hemoglobin levels. For bilateral TKA, a protocol of 2 preoperative autologous donation units and reinfusion of postoperative drainage reduces anemia during the preoperative and postoperative periods.

Adult↗
PubMed2005

Current trends in blood conservation in total knee arthroplasty.

There is a lack of consensus with regard to ways to minimize blood transfusions after total knee arthroplasty. We surveyed 434 members of the American Association of Hip and Knee Surgeons, each of whom averaged 18 years in practice and performed an average of between 100 and 150 knee replacements a year, about their preferences and practices regarding blood conservation during total knee arthroplasty. Of those surveyed, only 24% reported that there was a blood conservation program in place at their institutions. Fifty-nine percent of those surveyed routinely asked their patients to donate blood before unilateral and bilateral knee replacements. The amount of blood collected averaged 1.32 units (range, 1-4 units) and 2.04 units (range, 1-4 units) before unilateral and bilateral knee arthroplasty, respectively. Nearly half (47.5%) reported they rarely ever prescribed epoetin alfa because of a combination of cost, time, and labor issues. Furthermore, the majority (84%) has not had any experience with the use of antifibrinolytics. Overall, the mean transfusion rate after unilateral knee replacement was estimated to be less than 5% (range, 0%-20%) whereas the rate after bilateral knee replacement was estimated to be between 10% and 20% (range, 5%-20%).

Arthroplasty, Replacement, Knee↗
PubMed2005

The effect of total knee arthroplasty on body weight.

This prospective study quantified the weight change in 20 consecutive patients undergoing total knee arthroplasty. Resected bone, soft tissues, and bone reamings were collected during surgery and weighed using a digital scale at the end of the procedure. Results were compared to the cumulative weights of the prosthesis, bone cement, patellar component, and polyethylene liner. Average weight of the resected bone and soft tissues was 167.71 g for men and 130.13 g for women. Mean weight of the implanted prosthesis and cement used was 509.92 g for men and 422.56 g for women. Men tended to receive a larger-sized prosthesis than women. Overall, the average weight gain as a result of knee arthroplasty was 345.54 g for men and 292.44 g for women. This translates to an insignificant increase in body weight.

Aged↗
PubMed2004

The role of osteotomy 2003: defining the niche.

Although the use of traditional high tibial osteotomy in the unicompartmental osteoarthritic knee has declined due to high failure rates at 10 years, results that are generally poorer than total and unicompartmental arthroplasty, and difficulties with conversion to TKR, a potential role for osteotomy still exists. As long-term data becomes available to support or refute the renewed enthusiasm in the more modern techniques and applications, the indications for osteotomies about the knee will become better defined.

Arthroplasty, Replacement, Knee↗
PubMed2003

A quantitative histologic comparison: ACL degeneration in the osteoarthritic knee.

Newer prosthetic total knee arthroplasty (TKA) designs as well as unicondylar TKAs spare the anterior cruciate ligament (ACL). Although success of these procedures requires near normal ACL function, little has been written about the histologic features or the arthritic ACL. This study was designed to histologically evaluate the ACL for microscopic evidence of degeneration. Nineteen ACLs were harvested from 16 different patients who underwent TKA as a result of severe osteoarthritis. Control ligaments were obtained from bone bank donors (N = 14), patients with above-knee amputations (N = 5), and cadaveric formalin-preserved knees (N = 6). Orientation was maintained for each ACL. Degenerative parameters included loose, fibrous connective tissue and myxoid and cystic occurrences, and the presence of chondroid metaplasia or calcium phosphate crystals were evaluated and scored. Forty-seven percent of the osteoarthritic group had moderate/marked degeneration, whereas no control specimen showed such changes. Seventy-two percent of the controls were considered normal, compared with only 26% of the osteoarthritic group. Both of these findings were statistically significant (P<.001). Statistical analysis revealed no gender bias either within or between groups. In the control group, no statistical difference was found between patients older than age 65 and those younger than 65. In the osteoarthritic group, however, 70% of patients younger than 65 demonstrated moderate/marked changes compared with only 22% of those older than 65 (P<.05). There also was no difference demonstrated between the 4 focal sections of the ligaments that were examined.

Adult↗
PubMed2003

The role of debridement: through small portals.

Arthroscopic debridement represents one option for treatment of the patient with degenerative arthritis of the knee. Numerous procedures, including joint lavage, removal of loose bodies, partial meniscectomy, and techniques to stimulate cartilage repair may be included under this topic. Understanding surgical indications and clinical results requires differentiation of these individual components where possible. Furthermore, it is important to note that degenerative changes present along a spectrum of involvement. However, despite patient heterogeneity, selective application of conservative debridement, partial meniscectomy and removal of mechanical irritants will result in improved midterm follow-up results in approximately two thirds of patients. Patient expectations are crucial, and the temporizing nature of the procedure must be understood.

Arthroscopy↗
PubMed2003

Routine patellar resurfacing: a viable option.

The literature on routine patellar resurfacing documents that the rate of anterior knee pain after TKA is the same whether the patella is resurfaced or unresurfaced. The complication rate is different in these groups. In patients in whom the native patella is left, the rate of reoperation is approximately 10%. However, when correct surgical technique is used, the rate of patellar complications after routine resurfacing is negligible. Although design modifications have helped reduce patellar complications, the surgeon is the most important variable. As long as good technique is used, routine patellar resurfacing has been proven to produce the best results in TKA.

Arthroplasty, Replacement, Knee↗
PubMed2002

Blood management in revision total knee arthroplasty.

Much attention has been focused on blood management issues in orthopaedic surgery in recent years, but blood management in patients having revision total knee arthroplasty is not well-established. Hematologic values and transfusion records of 100 patients (52 women, 48 men; mean age, 65 years) who had aseptic revision total knee arthroplasty at the authors' institution were evaluated retrospectively. Two- or three-component revisions comprised 66% of the procedures, and 58 patients participated in a preoperative autologous donation program. The mean preoperative hemoglobin level was 12.1 g/dL in the women and 14.1 g/dL in the men, but the men experienced a greater decrease in hemoglobin level (mean largest decrease, 4.2 g/dL versus 3.1 g/dL), possibly caused by the higher allogeneic transfusion rate in women (19.2%) versus men (4.2%). Patient age did not influence hemoglobin level or transfusion rates. Patients who participated in a preoperative autologous donation program had significantly higher hemoglobin levels before donation (14.4 g/dL versus 13.3 g/dL for patients who did not participate in a program) but comparable hemoglobin levels after predonation (12.9 g/dL). Patients with preoperative hemoglobin levels less than 13 g/dL were significantly more likely to have a transfusion. Symptom-based transfusion strategies and blood management approaches such as epoetin alfa that elevate preoperative hemoglobin level therefore may be beneficial in patients having revision total knee arthroplasty.

Adult↗
PubMed2002

A fencepost solution.

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Arthroplasty, Replacement, Knee↗