John N. Insall

The posterior stabilized total knee prosthesis. Assessment of polyethylene damage and osteolysis after a ten-year-minimum follow-up.

The long-term results of use of the posterior stabilized total knee prosthesis were evaluated with regard to clinical performance, survival of the implant, polyethylene wear, osteolysis, and loosening. One hundred and twenty patients had 165 primary total knee arthroplasties, with insertion of a posterior stabilized total knee prosthesis with a metal-backed tibial component with cement, between March 1981 and March 1983. Thirty-seven patients (fifty-three knees) subsequently died, five patients (six knees) were lost to follow-up, three patients (three knees) refused evaluation, and one patient (two knees) was excluded because of severe medical debilitation. Thus, seventy-four patients (101 knees) were available for analysis. The mean age of the patients at the time of the operation was sixty-four years (range, twenty-two to eighty-one years). The mean duration of follow-up was ten years and eight months (range, ten years to eleven years and ten months). Preoperatively, the mean arc of motion was 94 degrees (range, 65 to 130 degrees), compared with 110 degrees (range, 90 to 145 degrees) at the latest follow-up examination. The mean knee score, according to the rating system of The Hospital for Special Surgery, was 51 points (range, 18 to 73 points) preoperatively, compared with 85 points (range, 0 to 100 points) at the latest follow-up examination. When the four knees that had a revision are excluded, the mean knee score, according to the rating system of the Knee Society, was 92 points (range, 67 to 100 points) and the mean functional score was 71 points (range, 0 to 100 points) at the latest follow-up examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomy of the epicondyles of the distal femur: MRI analysis of normal knees.

Knowledge of precise anatomic landmarks and relationships of the distal femur can be helpful in knee surgery, especially primary and revision total knee arthroplasty. We analyzed 104 consecutive routine knee magnetic resonance imaging studies to define useful landmarks and relationships. The epicondyles are described, and the relationship of the epicondyles to the joint line is defined in multiple planes. Some significant gender differences were noted. The distance from the epicondyles to the joint line correlates with the transepicondylar width of the distal femur. This information can be helpful in determining appropriate joint line position intraoperatively. The posterior condylar angle averaged 3.11 degrees for all patients, and a tendency for the posterior condylar angle to increase with age was noted, but further study of this tendency is needed.

Comprehensive Gait Analysis in Posterior-stabilized Knee Arthroplasty

Sixteen patients implanted with a posterior-stabilized prosthesis (Insall-Burstein PS II, Zimmer, Warsaw, IN) and 32 age-matched control subjects were evaluated by isokinetic muscle testing and comprehensive gait analysis at a mean 46 months following the index arthroplasty. The contralateral knee was normal in 13 patients and an asymptomatic total knee arthroplasty in 3 patients. No significant differences (P > .05) were found between the study and control groups in spatiotemporal gait parameters nor were there isokinetic strength deficits. A prolonged firing of the vastus medialis was observed in some patients. Knee range of motion during level walking and stair descent was decreased significantly (P < .05) in the study group. There was no significant difference for knee range of motion between the study and control groups during stair ascent. Spatiotemporal gait parameters in the total knee arthroplasty patients show no significant differences from the control subject at nearly 4 years after surgery. However, other gait abnormalities are present and cannot be accounted for on the basis of muscle weakness, abnormal phasic muscle activity, or inadequate knee range of motion. With reference to historic control subjects, the persistent gait abnormalities of patients implanted with posterior-stabilized prostheses (posterior cruciate substituting) are comparable to those of patients implanted with cruciate-retaining prostheses and superior to cruciate-sacrificing prostheses.

Randomized trial of epidural versus general anesthesia: outcomes after primary total knee replacement.

To compare the effects of epidural anesthesia and general anesthesia on early postoperative outcomes after unilateral primary total knee replacement, 262 patients were randomly assigned to receive either epidural or general anesthesia. All patients received a common rehabilitation protocol including a standardized assessment of progress. One hundred eighty-eight patients received a common thromboembolic prophylaxis protocol with postoperative aspirin, and had a standardized surveillance protocol to detect thromboembolic complications. Deep vein thrombosis was determined by venography on the operative limb, and pulmonary embolism was determined by comparison of preoperative and postoperative lung perfusion scans. The epidural anesthesia group reached all rehabilitative milestones earlier postoperatively than did the general anesthesia group, with a statistically significant earlier attainment of stair climbing. The incidence of deep vein thrombosis was 40% with epidural anesthesia, and 48% with general anesthesia. There were no clots proximal to the popliteal veins. The incidence of pulmonary embolism on lung scan was 12% with epidural anesthesia and 9% with general anesthesia. Epidural anesthesia is associated with more rapid achievement of postoperative in hospital rehabilitation goals after total knee replacement. A minor reduction in postoperative deep vein thrombosis rate was observed with epidural anesthesia, but this did not reach statistical significance. No difference in early postoperative pulmonary embolism was observed between the 2 types of anesthesia.

Resection Specimen Analysis of Proximal Tibial Anatomy Based on 100 Total Knee Arthroplasty Specimens

Although it is known that there is some asymmetry of the tibial plateau, most total knee arthroplasty designs currently have a symmetric tibial component. Using resection specimen analysis of the tibial plateau from 100 total knee arthroplasty specimens, the authors have examined the tibial plateau to further delineate, quantitatively, the medial and lateral tibial configuration. Unmagnified radiographs of each of the specimens were produced. A line was drawn along the mediolateral axis. The midpoint and points 10, 20, and 30% from the medial and lateral peripheries were then calculated. The average anteroposterior medial 10, 20, and 30% dimensions were 3.79, 4.74, and 5.06 cm, respectively. The average anteroposterior lateral 10, 20, and 30% dimensions were 3.48, 4.10, and 4.16 cm, respectively. The ratios of the lateral/medial anteroposterior distances at 10, 20, and 30% from the periphery were 92.10, 86.77, and 82.46%, respectively. A total knee arthroplasty system that recognizes the difference in the medial and lateral tibial plateaus and designs a prosthesis to account for the smaller, lateral tibial plateau may achieve the goal of maximizing tibial coverage as well as eliminate the problems associated with a symmetric design.

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.

Management of the chronic irreducible patellar dislocation in total knee arthroplasty

Neglected dislocation of the patella with gonarthrosis, genu valgum, flexion, and external rotation deformity is rarely encountered. Experience with five total knee arthroplasties in three patients with chronic patellar dislocation and gonarthrosis is reported. All knees had a modified proximal patellar realignment and arthroplasty with a constrained prosthesis. Preoperative Hospital for Special Surgery knee scores averaged 55. Average follow-up period was 40 months. At latest follow-up examination, the average Hospital for Special Surgery knee score was 83, the Knee Society knee score was 95, and the functional score averaged 50. There was one complication: a full-thickness lateral skin necrosis requiring flap coverage. The patellar score was zero in all knees. Four knees had mild quadriceps weakness. Three knees rated as excellent and two as good on both The Hospital for Special Surgery and Knee Society rating systems. Radiographic analysis revealed no radiolucent lines or osteolysis. The patellas were centralized in the trochlear groove in all patients. Patellar height averaged 14 mm (range, 12-17 mm). In conclusion, satisfactory results were obtained by restoring axial alignment with a constrained implant and realigning the patella with an extensive proximal realignment.

The patella in total knee replacement: does it matter?

nored the patello-femoral compartment. Patello-femoral complaints were common, and shortly thereafter designs appeared with a femoral trochlea and the option of resurfacing the patella with polyethylene. This is has become established today, but controversies remain about the need to resurface the patella in every case. In fact there are those who persuasively argue that the patella should never be resurfaced, citing no difference between having and not having a patella prosthesis and the additional potential for complications. Patello-femoral complications became an issue with the introduction of the metal-backed patellae components, which have now been abandoned with the exception of the rotating bearing type. Additionally, complications have been further lessened by attention to technical factors such as patella composite thickness, placement of the implant, rotational position and design of the femoral trochlea. I believe that pain relief is more complete with resurfacing, and that this should be performed routinely in the elderly. I have reservations in younger active and overweight persons and believe it wise to individualise in these cases, possibly taking into account the conditions of the articulation. Regarding the design of the patellar implant itself, “anatomical” shapes may offer theoretical advantages, but these are negated if patella alignment and tracking are not perfect. The “inset” patellae leaves a rather large area of uncovered patellar bone which may still cause symptoms. In the end there is much to be said for the traditional “dome” with three peg fixation, which has a long and successful clinical record. Although contact areas in the laboratory are small, wear has not been a clinical problem, probably because polyethylene has the property to adapt its shape due to cold-flow deformation. Knee Surg, Sports Traumatol, Arthrosc (2001) 9 [Suppl 1] :S2

Total Knee Replacement with Associated Extra-Articular Angular Deformity of the Femur

Review of the literature certainly does not reveal the most appropriate method for performing total knee arthroplasty in patients with extra-articular angular deformities due to the relative infrequency of this clinical problem. The primary goal of the surgeon should be attaining appropriate mechanical alignment in these difficult cases. The advantages of correction of the angular deformity at the joint line are the avoidance of an additional operative procedure for osteotomy and the risk of nonunion. Thorough preoperative planning is essential and deformity correction by osteotomy prior to arthroplasty should be performed in all femoral deformities that require bony resection above the level of the epicondyles for realignment of the mechanical axis. Attention to detail at the time of surgery should ensure that the bone resection of the distal femur and proximal tibial are perpendicular to the floor for correction of the mechanical axis and to prevent obliquity of the joint line. Posterior cruciatesacrifice and the understanding of appropriate soft tissue releases is mandatory for deformity correction using this method.

Draping Technique for Total Knee Arthroplasty

We find this method of draping to be very useful and have had no cases of sepsis in the immediate postoperative period. Such a draping technique, coupled with laminar flow, occlusive exhaust suits, and appropriate antibiotics may actually save OR and anesthesia time, and may be more cost effective and safer for the patient because it may serve to reduce the risk of cross-contamination between patient and staff, thereby minimizing the risk of infection.