Purpose of the study: Changes in prosthetic design to adapt to knee flexion greater than 120 degrees can modify the bone-prosthesis fixation and also displace the femorotibial contact. The purpose of this study was to analyze mid-term results in a consecutive series of 186 arthroplasties and to examine the femorotibial kinematics in vivo.

Material and methods: A posterior stabilized cemented prosthesis with a plateau with motion limited to rotation was used. Design changes concerned: lengthening of the posterior femoral condyle, scooping out the poly-ethylene anteriorly with reorientation and change in the height of the posterior stabilization stem. The same technique was used for all patients who followed the same rehabilitation protocol. Mean age was 69 years (range 22–87). All patients were evaluated clinically with the IKS score and radiologically on the anterioposterior and lateral images. An in vivo analysis of the femorotibial kinematics in the weight bearing condition was also performed in 20 patients under fluoroscopic control with automatic 3D modelization.

Results: Mean follow-up was 40 months (range 2–5 years). Mean IKS function score improved from 34 preoperatively to 96 at last follow-up. The knee score improved from 53 on average to 91 at last follow-up. The mean flexion was 115° (range 45–135°) preop-eratively and 120° (115–145°) at last follow-up. One implant was removed for infection and arthrolysis was performed for one case of stiff joint. Radiographically: the mean postoperative femorotibial alignment was 179° (178–181°), the mean tibial slope 3.8° (0–10°°, the mean patellar height (0.8° (0.56–1°), and the mean elevation of the joint space (4.5 mm. There were two cases of progressive lucent lines in the tibial zone which were stable at last follow-up. All patients analyzed showed a mean posterior displacement of the femorotibial point of contact of 9.7 mm at flexion.

Discussion and conclusion: Changes in prosthesis design to adapt to greater range of flexion do not appear to have a negative effect at mid-term on implant fixation. The clinical flexion ranges obtained were encourageing and the correlation with kinematic results show that the degree of preoperative flexion remains a determining factor for the postoperative outcome. Posterior displacement of the femoro-tibial point of contact, observed in all patients examined fluoroscopically, certainly contributed to the good postoperative flexion.

Purpose: During the second half of the 80s, Grammont, Trouilloud and Guichet developed a centromedullary nail for progressive limb lengthening. We analysed retrospectively twenty lengthenings, studying the clinical and radiological results to examine the quality of callus formation.

Material and methods: This study included eighteen patients, thirteen men and five women, who underwent lengthening procedures between 1991 and 2000. The patient’s clinical files were analysed in addition to the results of a physical examination. A standardised x-ray protocol was used to analyse bone regeneration.

Results: Mean follow-up was 4.55 years (1.5–10.5). Mean lengthening was 46 mm (30–80) achieved at a mean rate of 1.28 mm/d. The Bastiani index was 26 j/cm. Complications were: one progressive external popliteal sciatic palsy, one persistent knee flexion, one premature callus consolidation, and two callus fractures after nail removal. All patients maintained their activity level. The quality of regenerated bone was better in the dorsal and medial segments exposed to more stress. The callus was cortical and remodelled after removal of the nail.

Discussion: Like all lengthening techniques, the Albizzia nail requires careful preoperative planning, particularly to determine the level of the endomedullary osteotomy. The clinical results in this series were globally satisfactory. The callus was similar to cortical bone and quite different from the callus obtained with external lengthening methods, but our study demonstrated the excellent quality of the regenerated bone. The Albizzia nail can also be left in place until a solid reliable callus has formed, an advantage compared with external fixation which is less well tolerated.

Purpose: Patellar instability raises serious clinical and therapeutic problems in children. We present our results with the “soft baguette” technique used since 1974.

Material and methods: Sixty-four patients (50 girls and 14 boys) (85 knees) treated between 1974 and 2000 were reviewed. Mean follow-up was 140 months (14–234). For eight knees, section of the lateral wing of the patella was associated. The five types of patellar instability, from permanent dislocation to potential instability, were represented.

Results: At last follow-up, 84% of our patients were satisfied with significant improvement in pain, instability and patellar track. We had minor complications in 23.5% of the knees (haematoma, effusions) and eleven recurrences (9.5%) at mid- or long-term which were considered failures. There were no cases of epiphysiodesis. A neoTTA developed in eight cases, proving the efficacy of realignment of the medialised patellar ligament. Following changes in the mechanical axis of these knees revealed a clear trend towards increased valgus.

Discussion: The soft baguette technique has fulfilled expectations: stabilisation of the extensor system without injuring the growth cartilage, and trochlear remodelling for the younger patients. The trend towards increased valgus raises a problem. Because of this risk, if the initial valgum is greater than 5° we emphasise the theoretical importance of temporary medial epiphysiodesis associated with the soft baguette to control this potential source of recurrence and therapeutic failure.

Purpose: The current concern to achieve 120° postoperative flexion in certain patients raises the problems of polyethylene wear, prosthesis stability, and surgical technique. The purpose of this clinical and radiographic comparative study was to analyse pertinent factors

Material and methods: We studied two groups of posterior stabilised total knee prostheses with mobile plateaux. In group A (23 knees), the plateau had rotatory and translation mobility. In group B (36 knees) the plateaux only had rotatory mobility and the posterior condyle was long. We studied clinical flexion before surgery and postoperatively at one year. The radiographic analysis included: mechanical axis, height of the articular space, patellar height, anteroposterior prosthetic surface. In both groups the patients had undergone medial parapatellar arthrotomy and had participated in the same rehabilitation programme.

Results: There was no statistically significant difference between the two groups for age, gender, weight, height, pre-operative diagnosis, or preoperative flexion (mean 120.8°, range 90–130° in group A and mean 120.7°, range 90–140° in group B). Mean postoperative flexion was 114.8° (50–140°) in group A and 130.4° (90–150°) in group B. The difference was statistically significant. There were two episodes of instability in group A and none in group B. There was no difference concerning the pre- or postoperative axis or patellar height. There was a difference in articular space height and anteroposterior prosthetic surface.

Discussion: The gain in flexion achieved in group B is related to the smaller anteroposterior prosthetic surface and the more systematic use of distractors to clear the posterior part of the knee. The design of the posterior condyle could also be involved, allowing better congruence beyond 120°. The difference in stability between the two groups could be related to a difference in the distance between the apex of the tibial attachment and the posterior stabilisation cam. This study demonstrated that increased flexion is possible after total knee arthroplasty in certain patients. It is related to surgical technique but also has direct implications for prosthesis design.

Purpose: We performed a biometric evaluation of the femoral trochlea in the human foetus and compared measurements with those observed in the adult in order to search for correlations with other biometric parameters of the human femur.

Material: Twenty-two foetuses with no orthopaedic anomalies were preserved in formol. The 44 knees were studied. Fœtal age varied from 26 to 40 weeks.

Method: After anatomic dissection, digital photographic documents were analysed using angular measurement software. The following dimensions were measured on the distal epiphysis: anteroposterior thickness of the condyles, protrusions of the lateral and medial trochleal edges, the difference in condyle height, the trochlear opening angle alpha, trochlear slope. Femoral anteversion, length of the femoral neck, and the neck-shaft angle were measured on the AP view of the femur.

Spearman’s test was used to search for correlations. Results were compared with those measured under the same conditions in a series of 32 adult knees published by Wanner.

Results: The alpha angle of trochlear opening was 148° with a coefficient of variability of 4%. The alpha angle was greater than 150° in 18 trochleae. The lateral edge of the trochlea was higher than the medial edge in 37/44 trochleae. There was no correlation by age and sex.

The femoral measurements showed 27.01° anteversion with very wide variability (coefficient 46%) and no correlation with trochlear opening.

No significant differences were observed between the fœtal and adult measurements.

Discussion: Our data are the first reporting anatomic measurements of the fœtal trochlea. The morphology of the lower extremity of the femur during the third trimester of pregnancy is globally the same as in adult femurs. Morphological changes of the proximal femur occurring during growth do not appear to modify the morphology of the distal femur. The deep and asymmetrical engagement of the patella onto the trochlea is a characteristic of modern man and is considered to be a consequence of bipedal stance. Our study would appear to confirm that the anatomic characteristics of the human trochlea have been integrated into the genome in the course of evolution. This suggests that a genetic origin of trochlea dysplasia, as suggested by Dejour, is a reasonable hypothesis.

This comparative clinical and radiographic study evaluates the role of implant design and positioning on maximum postoperative flexion after TKR.

Two groups of cemented posterostabilised mobile prosthesis were studied. In group A (23 cases) bearing mobility was possible in rotation and translation. In group B (36 cases) solely rotation was possible and the radius of the posterior femoral condyle was larger. In both groups the same medial transquadricipital approach was used and the postoperative rehabilitation was identical.

There were no significant difference between the two groups for patient age, sex, weight and etiology. The average preoperative flexion was 120.8° in group A and 120.7° in group B. The average postoperative flexion at one year was 114.8° in group A and 130.4° in group B. Instability was noted twice in group A and none in group B. Radiographically there was no difference in mechanical axis or patellar height. There was a difference in joint line elevation and anteroposterior joint size.

Higher flexion angle may be related to smaller antero-posterior joint size, better posterior osteophytes removal and larger posterior femoral condyle radius. Greater stability correlates with greater jumping distance over the tibial post. This study showed that deep flexion can be achieved in some patients after TKR, with implications on surgical technique and implant design.