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.

The influence of femoral component design in the elimination of patellar clunk in posterior-stabilized total knee arthroplasty.

Patellar clunk occurs after posterior-stabilized total knee arthroplasty and is believed to be a design-related complication. This study was undertaken to define the incidence of patellar clunk with an optimized third-generation, posterior-stabilized prosthesis. One hundred ninety three patients with 238 knees were evaluated at a minimum of 2 years after primary total knee arthroplasty with a cemented, NexGen Legacy Posterior-Stabilized prosthesis (Zimmer, Warsaw, Ind).

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.

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.

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.

Factors affecting postoperative range of motion after total knee arthroplasty.

One hundred thirty five patients with osteoarthritis who underwent total knee arthroplasty (TKA) were evaluated to determine whether specific pre- and postoperative variables were correlated with the postoperative range of motion. Age, sex, pre- and postoperative range of motion, pre- and postoperative Knee Society scores, intraoperative patellar thickness before and after resurfacing, pre- and postoperative radiographic patellar height (as determined by the Insall-Salvati and Blackburn-Peel ratios), and preoperative radiographic alignment were recorded for each patient. Regression analysis was performed to identify whether any variables were correlated with the postoperative range of motion or Knee Society scores.

Optimizing patellofemoral tracking during total knee arthroplasty.

Fifty-seven patients who underwent 65 primary TKAs between 1993-1994 were retrospectively studied to identify the technical challenges and pitfalls associated with patellar resurfacing and to improve patellar tracking during total knee arthroplasty (TKA). Average patient age was 69 years. All surgeries were performed by a single surgeon (J.

Flexion-extension gap changes during total knee arthroplasty: effect of posterior cruciate ligament and posterior osteophytes removal.

Flexion and extension gap heights were measured in 50 consecutive primary posterior-stabilized total knee arthroplasties (TKAs) to determine whether posterior cruciate ligament (PCL) release or re-establishment of the posterior condylar recess increased gap width. After PCL release, a slight symmetrical increase was noted in both gaps. In extension, gap width increased on average 1.

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.

The impact of femoral component rotational alignment on condylar lift-off.

The surgical technique and implant design influence femoral condylar lift-off in total knee arthroplasty. With the use of the classic method of bone resection and appropriate soft tissue releases, alignment of the femoral component along the transepicondylar axis will create a symmetric and balanced flexion space. This surgical technique will reduce the incidence of condylar lift-off.

Revision total knee arthroplasty: a surgical technique.

The etiology of surgical failure should be defined before revision total knee arthroplasty (TKA) is contemplated, since revision surgery without a clear reason may fail to correct the underlying problem. The causes of mechanical failure include component loosening, instability, polyethylene wear, component malposition, extensor mechanism dysfunction, and loss of motion. Revision that is required because of an infection is also acomplex situation, which requires skill and meticulous technique in order to restore a functional outcome.

Assessment of backside wear from the analysis of 55 retrieved tibial inserts.

Fifty-five retrieved tibial inserts with four different locking mechanisms were evaluated for evidence for polyethylene wear between the inferior surface of the tibial insert and metal tray. This type of wear will be referred to as backside wear. Backside wear was assessed by evaluating manufacturer's stamped markings on the inferior polyethylene surface.

Correlation between condylar lift-off and femoral component alignment.

The current study analyzed subjects having a total knee arthroplasty to determine the incidence of condylar lift-off and correlate lift-off with the alignment of the femoral component with respect to the transepicondylar axis. Twenty-five subjects, implanted with a posterior stabilized total knee prosthesis, were asked to do weightbearing deep knee bends while under fluoroscopic surveillance. The two-dimensional fluoroscopic images were converted into three-dimensional images using a fully automated computer model-fitting technique.

Mobile bearings in primary knee arthroplasty.

Mobile-bearing knee arthroplasty (MBKA) has potential advantages compared with conventional fixed-bearing total knee arthroplasty (TKA). By allowing unconstrained axial rotation, MBKA can offer greater articular conformity without an increased probability of loosening due to increased axial torque. Increased articular conformity minimizes polyethylene contact stresses, thereby reducing linear wear and subsurface fatigue failure.

Does modularity affect clinical success? A comparison with a minimum 10-year followup.

A comparison of the clinical and radiographic results of patients with metal-backed monoblock Insall-Burstein I and modular Insall-Burstein II Posterior Stabilized Knee Prostheses was done. The minimum followup was 10 years. The clinical results were comparable with a similar average Hospital for Special Surgery knee score of 85 and 84 points, respectively.

Mobile-bearing knee replacement: concepts and results.

In summary, if TKRs are to be performed in patients who are younger and more active than those who had the initial procedures in the 1970s and 1980s, better wear performance is imperative for long-term durability, especially if surgeons continue to consider the versatility associated with modular knee-replacement systems to be a necessity. At least with some designs, including the Oxford knee and the LCS knee, the results after a minimum follow-up of 10 years are comparable with the best results after arthroplasty with fixed-bearing designs in terms of wear, loosening, and osteolysis (Table 7). As with fixed-bearing designs, there are additional challenges in terms of optimizing bearing-surface conformity and improving kinematics.

Accuracy of soft tissue balancing in total knee arthroplasty.

To the best of our knowledge, this is the first study to assess the accuracy of balancing of the flexion and extension gaps in total knee arthroplasty (TKA). Measurements of the heights of the flexion and extension gaps were obtained during 104 consecutive primary, posterior-stabilized TKAs in osteoarthritic patients. Clinically, all knees appeared to be well balanced intraoperatively.

Primary constrained condylar knee arthroplasty for the arthritic valgus knee.

The purpose of the current study was to review results of primary constrained condylar knee arthroplasty in elderly patients with genu valgum deformity. The hypotheses were: (1) constraint has no adverse effects in elderly patients; (2) treating deformity with a constrained condylar knee prosthesis in lieu of lateral ligament release avoids morbidity, particularly peroneal nerve palsy and flexion instability; and (3) press-fit noncemented stem extensions enhance fixation of the cemented core components and are not prone to loosening. Between 1988 and 1993, 44 consecutive primary Constrained Condylar Knee prostheses were implanted in 37 patients (average age, 72.