Whether it is best to retain the posterior cruciate ligament in the degenerated knee, i.e. using a cruciate-retaining (CR) total knee prosthesis (TKP), or to use a more constraint posterior-stabilized (PS) TKP is of debate. There are limited studies comparing the effect of both methods on implant fixation and clinical outcome, leaving it up to the surgeon to base this decision on anything but conclusive evidence. We assessed the effect of two different philosophies in knee arthroplasty on clinical outcome and tibial component migration measured with radiostereometric analysis (RSA), by directly comparing the CR and PS version of an otherwise similarly designed cemented TKP.

Sixty patients were randomized and received a Triathlon TKP (Stryker, NJ, USA) of either CR (n=30) or PS (n=30) design. RSA measurements (primary outcome) and clinical scores including the Knee Society Score and Knee injury and Osteoarthritis Outcome Score were evaluated at baseline, at three months postoperatively and at one, two, five and seven years. A linear mixed-effects model was used to analyse the repeated measurements.

Both groups showed a similar implant migration pattern, with a maximum total point motion at seven years follow-up of around 0.8 mm of migration (mean difference between groups 95% CI −0.11 to 0.15mm, p=0.842). Two components (one of each group) were considered to have an increased risk of aseptic loosening. Both groups improved equally after surgery on the KSS and KOOS scores and no differences were seen during the seven years of follow-up.

No differences in implant migration nor clinical results were seen seven years after cruciate-retaining compared to posterior-stabilized total knee prostheses.

Objectives

The objective of this study was to compare the early migration characteristics and functional outcome of the Triathlon cemented knee prosthesis with its predecessor, the Duracon cemented knee prosthesis (both Stryker).

Introduction

When introducing new joint replacement designs, it is difficult to predict with any certainty the clinical performance of the new designs. Using roentgen stereophotogrammetric analysis (RSA) to evaluate the first two years of follow-up can serve as a predictor of late mechanical loosening for hip and knee prostheses. This prospectively randomized study was designed to evaluate the clinical performance of the Triathlon total knee system and compare the results between the two versions; posterior stabilized (PS) and cruciate retaining (CR).

Introduction: When introducing new joint replacement designs, it is difficult to predict with any certainty the clinical performance of the new design. Using roentgen stereophotogrammetric analysis (RSA) to evaluate the first two years of follow-up may serve as a predictor of late mechanical loosening for both hip and knee prostheses. This randomized study was designed to evaluate the performance of the new Triathlon total knee system and compare the results to its predecessor design, the Duracon total knee system.

Methods: Sixty patients were consecutively randomized to receive either a Duracon (30 patients) or Triathlon total knee (30 patients). All components were cemented, and the posterior Cruciate Retaining version was used for both systems. The study was approved by the Ethical Committee for Lund University. All patients met the inclusion criteria. The mean age was 66 years (Duracon) vs 67 years (Triathlon). The BMI was 29 for both groups. The left knee was operated on in 15 vs 18 patients for the Duracon and for the Triathlon group. There were no statistically significant differences between the demographics for the two groups, except for the number of Ahlbäcks grade III OA, 20 (Duracon) vs 28 (Triathlon). The mean duration of surgery was 64 minutes (Duracon) vs 67 (Triathlon). The hospital stay was 5 days for both groups. The patients were followed up postoperatively at 3, 12 and 24 months. The principal evaluation tool was RSA to measure migration. The clinical results were evaluated using KOOS and KSS.

Results: There were no significant differences in rotation or translation for the three coordinal axes. Neither were there any significant differences in the Maximal Total Point Motion (MTPM) during the 2-year follow-up The MTPM for the Duracon and Triathlon groups respectively was 0.5±0.5 vs 0.4±0.3 mm at 3 months, 0.6±0.4 vs 0.6±0.5 mm at 1 year, and 0.8.±5 vs 0.6±0.7 mm at 2 years. There were no significant differences in the clinical results between the groups when using the KSS and the KOOS.

Discussion: The results of this study suggest that the new Triathlon total knee system is at least clinically equivalent to the Duracon total knee system. There were no significant differences in the RSA 2-year follow-up data nor in the clinical data (p< 0.05), which suggests the Triathlon knee system may replicate the excellent long-term clinical results achieved by the Duracon knee system.

In living normal knee the lateral femoral condyle rolls posteriorly more than the medial side to the extent that in deep flexion the lateral femoral condyle sublux from the tibial surface (Nakagawa et al). The purpose of this presentation is to study the tibiofemoral movement in patients who had full flexion after total knee replacements and to compare it with that of normal knee.

23 knees were scanned using SIEMENS SIREMOBILE Iso-C with 3D Extension C-arm. The system is able reconstruct 3D images that can be viewed from deferent angle and precise measurements of distances between the deferent components of the implant can be made. The knee was scanned while the patient is sitting in kneeling position with the calf touching the thigh (flexion of over 150degree

All the cases studied showed a variable roll back between the medial and lateral femoral condyle. In all cases the lateral roll back was much more than the medial. In 14 cases we confirmed lateral condyle subluxation similar to what is seen in normal knee. The position of the foot (internal or external rotation) during scanning did not affect the lateral femoral condyle role back.

Although previous studies have shown paradoxical types of tibiofemoral movement in patients who have total knee replacements throughout the range of movement, the knees in patients who had full flexion after TKA tend to have the same tibiofemoral movement as the normal knee in deep flexion. The lateral femoral condyles spin off or subluxation could adversely affect the implant components especially if the design does not accommodate this movement. The lateral femoral condyle may sublux from the tibia during kneeling inpatients who had full flexion after TKA. These findings should call for changes in the implant design to accommodate the lateral condyle roll back.

Introduction: In living normal knee the lateral femoral condyle rolls posteriorly more than the medial side to the extent that in deep flexion the lateral femoral condyle sublux from the tibial surface(Nakagawa et al). The purpose of this presentation is to study the tibiofemoral movement in patients who had full flexion after total knee replacements and to compare it with that of normal knee.

Materials and Methods: 23 knees were scanned using SIEMENS SIREMOBILE Iso-C with 3D Extension C-arm. The system is able reconstruct 3D images that can be viewed from deferent angle and precise measurements of distances between the deferent components of the implant can be made. The knee was scanned while the patient is sitting in kneeling position with the calf touching the thigh (flexion of over 150degree).

Results: All the cases studied showed a variable roll back between the medial and lateral femoral condyle. In all cases the lateral roll back was much more than the medial. In 14 cases we confirmed lateral condyle subluxation similar to what is seen in normal knee. The position of the foot (internal or external rotation) during scanning did not affect the lateral femoral condyle role back.

Discussion: Although previous studies have shown paradoxical types of tibiofemoral movement in patients who have total knee replacements throughout the range of movement, the knees in patients who had full flexion after TKA tend to have the same tibiofemoral movement as the normal knee in deep flexion. The lateral femoral condyles spin off or subluxation could adversely affect the implant components especially if the design does not accommodate this movement.

Conclusion: The lateral femoral condyle may sublux from the tibia during kneeling in patients who have full flexion after TKA. These findings should call for changes in the implant design to accommodate the lateral condyle roll back.

The success of a high tibial osteotomy is predicted on proper patient selection, achievement and maintenance of adequate correction and avoidance of complications. It is a successful procedure when the patient’s pain is reduced or eliminated, the knee movement is preserved, and the need for a joint replacement is eliminated or postponed.

475 open wedge procedures using the hemicallotasis technique (HCO) were followed consecutively since a progressive introduction 1993. All patients were followed and compiled in a data base, 307 men, 168 women were included. The indications were arthrosis 439, sequels of fracture 12, correction 12, seqv osteotomy 7, others 5. For the arthritic knees 343 were med gr 1–3 343, med gr 4–5 35, lat arthrosis 37, prearthrosis 4. 32 patients were bilateral operated at one session.

The surgical technique is simple, using a ventral external fixator – the Orthofix T Garche. The technique is in principle extra articular. The patients were followed once/week and complications were compiled. The patient’s perspective of the HCO were evaluated for 58 patients using the KOOS questionare.

Complications as reoperation with reposition of pins 9 cases, septic arthritis 6, non-union 11, early loss of correction 5, nerve palsy 3 (all regress), interrupted treatment 3, DVT 10. For all complications including pin site infection, smoking were the single greatest preoperative risk factor (p< 0.022). 27 patients operated by HCO were converted to a joint replacement. The mean frame time was 99 + 20 days, 94/466 had a frame time > 16 weeks (smoking< 0.001). The patients self asessment were improved during treatment for the KOOS subcategories pain, function, ADL and Quality of life, but during treatment there were no improvement in sport/recreational function.

We found the HCO technique good, surgicallysimple, but there is a need for a close contact between the patient and the treatment team. This technique is probably the best when doing corrections greater than 15 degree. The largest single correction was 33 degree. The risk for septic arthritis using in a principle extra articular technique has to be considered.