Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has largely been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e. whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA.

We analysed the shape of 114 arthritic knees at the time of primary TKA using the pre- operative CT scans. The aspect ratio and trapezoidicity ratio were quantified, and the post- operative prosthetic overhang was calculated. We compared the morphological characteristics with those of 12 TKA models.

There was significant variation in both the aspect ratio and trapezoidicity ratio between individuals. Femoral trapezoidicity was mostly due to an inward curve of the medial cortex. Overhang was correlated with the aspect ratio (with a greater chance of overhang in narrow femurs), trapezoidicity ratio (with a greater chance in trapezoidal femurs), and the tibio- femoral angle (with a greater chance in valgus knees).

This study shows that rectangular/trapezoidal variability of the distal femur cannot be ignored. Most of the femoral components which were tested appeared to be excessively rectangular when compared with the bony contours of the distal femur. These findings suggest that the design of TKA should be more concerned with matching the trapezoidal/ rectangular shape of the native femur.

Purpose of the study: The aim of this study was to report outcome after more than six years follow-up of a series of 122 unicompartmental prostheses.

Material and methods: Cemented HLS® unicompart-mental surface-coated prostheses were implanted in 111 patients (122 knees, 88% medial and 12% lateral) between January 1995 and November 1997 by the same surgeon. These knees presented unicompartmen-tal osteoarthritis (91%) or unicondylar necrosis (9%). An independent senior surgeon reviewed 94 prostheses. Seventeen patients died and ten institutionalized patients free of complaints about their knee could not be fully assessed. Only three patients (2.7%) were lost to follow-up). Clinical data were assessed with the IKS criteria. A complete radiological work-up was available to compare preoperative images with the last follow-up results. Mean follow-up was 88 months (range 72–108 months).

Results: After the implantation, 96% of patients were satisfied or very satisfied; 84% had no or little pain. Mean flexion was 133° (range 90–150°). The mean knee score at follow-up was 86/100 (40/100 preoperatively), mean function score 77/100 (61/100 preoperatively). Mean residual misalignment was 6° (7° varus for medial prostheses and 4° valgus for lateral prostheses). Tibial or femoral lucent lines were observed for 22% of the prostheses but with no change and no clinical expression. There was one case of tibial polyethylene wear (1mm). There were eight failures (all before 24 months) with revision with a total knee arthroplasty (two infections, one overlarge component, two tibial loosenings, 3 unexplained pain). The Kaplan-Meier survival at maximum follow-up of 108 months was 93.67%.

Discussion: The prostheses implanted in this series were correct indications according to the preceding symposiums. We analyzed the clinical and radiological outcome (overall axial correction, tibial and femoral correction), failures, and reasons for incomplete results.

Conclusion: Outcome at more than six years in this series of resurfaced knee prostheses with a polyethylene plateau was good, supporting the correct choice of implant and technique. These results also enabled validation of the principle that unicompartmental arthroplasty is a valid alternative for the treatment of unicompartmental osteoarthritis of the knee joint. Analysis of the failures and the incomplete results discloses interesting avenues for optimizing the surgical technique and improving future clinical and radiological results.

Purpose: The purpose of this study was to analyse the clinical and MRI results of anterior cruciate ligament (ACL) grafts using the patellar tendon with a tibial fixation by th resorbable interference screw PLA 98 (Phusis(r)).

Material and methods: ACL grafts were performed in 182 patients between 1994 and 1997. A unique graft was used in 85 cases (Kenneth Jones), and association with Lemaire plasty in 97. The tibial fixation was achieved with the resorbable screw in all cases. Clinical and radiological data were recorded before surgery, and at one and five years. Among the 110 patients with an MRI at one year, 62 also had an MRI control at five years (57%). The antero-posteior and mediolateral tibial position was evaluated on the horizontal slices. We defined a method for evaluating the femoral position on the horizontal MRI slices. The aspect of the graft was analysed at one and five years.

Results: There were three failures (Trillat-Lachmann test). Mean residual differential laxity was 2.6 mm (Telos). At five years, 92% of patients practiced sports at a moderate or intensive level. The tibial position was good and highly reproducible (SD=0.06). Five femoral positions were not satisfactory but were not related with failure. All screws were resorbed at five years. There were two bone reactions at one year, with no relation with screw absorption (one contusion and one reflex dystrophy). At one year, the MRI with gadolinium injection visualised peripheral enhancement of the graft. At five years three transplants appeared heterogeneous, corresponding to three ruptures. Segmentary heterogenic aspects were not found to have any pathological significance.

Discussion: Evaluation of the femoral position is difficult on the MRI sagittal views. Our analysis method based on horizontal slices allowed reliable reproducible analysis. Analysis of the graft should take into consideration the time since surgery and the sequence used. There was no problem with fixation or screw absorption.

Conclusion: MRI follow-up of ACL grafts enables an analysis of the transplant positions, to follow the evolution of the graft, and to confirm the reliability and safety of the resorbable screw fixation.

Purpose: One of the difficult problems during the implantation of a total knee prosthesis is the presence of preoperative stiffness or permanent flexion.The later is a sign of advanced stage degradation due to osteoarthritis or rheumatoid arthritis. We wanted to describe the technical specificities of a total knee arthroplasty (TKA) implanted in patients with permanent flexion and to analyse long-term outcome.

Material and methods: We studied a series of 826 posterior stabilised TKA (HLS) implanted since 1988 (followed prospectively since 1995). We defined three groups of patients according to the degree of preoperative flexion: group I (0°–10°), group II (11°–20°), and group III (> 20°). We evaluated the operative technique itself, then analysed long-term clinical and radiological outcome using the IKS scores.

Results: There was no significant difference in the objective or subjective clinical or radiological outcomes in the first two groups (I and II). Outcome appeared to be less satisfactory in patients with permanent flexion greater than 20°, but the statistical analysis was not feasible.

Discussion: This study enabled us to describe the specific preoperative planning and the operative steps necessary for patients with permanent flexion preoperatively. The results of our series do no enable distinction between the long-term results in patients with < 20° flexion. Beyond this level, techniques for bony or ligamentary release influence the results which are less satisfactory. Posterior stabilisation enables release of the posterior cruciate ligament in order to improve joint recovery.

Conclusion: Preoperative planning for TKA must of course take into account bony deformation, but also preoperative joint motion. In the event of permanent flexion, the operative technique must be adapted. This allows correct position of the implant and improved joint motion.

Purpose: The purpose of this work was to report mid-term results of a series of 162 total knee prostheses with an all-polyethylene plateau.

Material and methods: Between 1989 and 1995, 162 posterior stabilised cemented HLS2 total knee prostheses with an all-polyethylene plateau were implanted during first intention arthroplasties performed by the same surgeon. 142 prostheses were reviewed at more than one year, three patients died, and 17 were lost to follow-up (10%). Clinical results were assessed with the IKS criteria. Complete x-ray data included pangonograms. Mean follow-up was 4.5 years.

Results: Ninety-six percent of the patients were satisfied or very satisfied and 95% had no pain or mild pain. Mean flexion was 114°. The mean postoperative knee score was 81/100 and mean function score was 64/100. Radiographic findings showed the good position of the implants with mean AFT at 178.6°, mean AFm at 89.1° and mean ATm at 89°. There were eight failures (4.9%) requiring replacement of a component, two for frontal laxity, three for patellar fracture, one for infection, one for aseptic loosening, and one for an oversized tibial plateau. Two revision procedures were performed without implant replacement, one for pain (biopsy) and one for arthrolysis.

Discussion: These 162 prostheses with an all-polyethyl-ene plateau were retained among a consecutive series of 893 HLS prostheses. We compared the present results with those of the metal-backed prostheses implanted in this series and with data in the literature. We found a significant correlation between the presence of tibial lucent lines and postoperative alignment defects, explained by the type of tibial component, in these 162 all-polyethyl-ene plateau prostheses. These lucent lines did not progress with time and had no clinical consequence.

Conclusion: Clinial and radiological results with total knee prostheses with an all-polyethylene plateau, i.e. without metal backing, were very good in this series. We analysed our experience in comparison with the literature, focusing on the advantages and disadvantages of these two types of components.