Mobile-bearing total knee arthroplasty was developed to provide low contact stress and reasonably unrestricted joint motion. We studied the results of a cementless, posterior cruciate ligament (PCL)-retaining total knee arthroplasty (TKA), with a mobile-bearing insert in rotation and anterior-posterior (AP) translation (Innex® Anterior-Posterior Glide, Zimmer). Kinematic analyses were performed on a series of 51 primary TKA. The patients’ mean age was 71±8 years at operation. Patients were studied at 23 months average follow-up with weight-bearing radiographs at full-extension, 30° flexion and maximum flexion (“lunge” position). Three dimensional position and orientation of the mobile-bearing relative to the femoral and the tibial component during flexion were determined using model-based shapematching techniques. The average weight-bearing range of implant motion was 110°±14°. In flexion, the mobile-bearing was internally rotated 3°±3° with respect to the femoral component (p<
0.0001) and the tibial tray was internally rotated 5°±7° with respect to the mobile-bearing (p<
0.0001). On average, the mobile-bearing did not translate relative to the tibial base plate from full extension to 45° flexion [0±2 mm (range −5 mm to 6 mm)]. However, the mobilebearing did translate anteriorly 1±2 mm (range −2 mm to 9 mm, p<
0.0001) between 45° flexion and maximal flexion. We conclude that the mobile-bearing insert showed a progressive increase in internal rotation during flexion. Most of this rotational mobility occurred between the mobile insert and the tibial base plate. With flexion, AP translation did occur between the femoral component and mobile-bearing, and between the mobile-bearing and tibial base plate, but mobile-bearing translation was unpredictable with this unconstrained design.
1 (9.6%) and in 4 (1.7%) in group 2. The difference was significant. Presence of a history of dystrophy was significantly associated with development of dystrophy (RR=10.4). A psychological context appeared to increase the risk of dystrophy (RR 2.6) but did not reach significance. There was no statistical relationship with age, gender, duration of tourniquet, type of disease condition, or surgical procedure performed.
For clinical evaluation, we used the IKDC score (1999), and laxity measurement with the KT-1000 arthrometer and stress X-rays. The mean follow-up was 24 months.
We found no statistical difference between the three groups of graft used for revision. The results are a trend toward less good results, when patients had a meniscec-tomy. Subjectively the result were worse in cases of cartilage lesion. In fact, no patient who had grade IV lesion returned to there previous level activity (pre-operative level activity). The worse results are in the group of failed synthetic ligaments.
There was no clinical difference for the revision, whether we used autograft of patellar tendon, quadriceps tendon or hamstring tendon with an adapted fixation device. On the other hand, meniscal or cartilage lesion or the use of synthetic grafts are factors of poor clinical outcome.
All radiograms were digitalised (Vidar VXR-12 plus) and analysed by four observers using the FootLog software which provides semiautomatic measurements. The following parameters were recorded: distance between the lateral sesamoid and the second metatarsal (LS-M2), the M1P1 angle (for the diaphyseal and mechanical axes of M1), the diaphyseal and mechanical distal metatarsal articular angle (DMAA) of M1, Meschan’s angle (M1–M2–M5), the distance between a line perpendicular to the axis of the foot drawn through the centre of the lateral sesamoid and the centre of the head of M4 (MS4–M4) (a corrective factor was introduced for the MS4–M4 distance to account for the displacement of the lateral sesamoid in hallux valgus), the M1 index = d1-D2 (length of the head of M1/MS4 – length of the head of M2/MS4), maestro 1 = d2–d3, maestro 2 = d3–d4, maestro 3 = d4–d5. The measured parameters were recorded automatically on an Excel data sheet and statistical analysis was performed with SPSS 9.0.