562 osteoarthritic knees rated as stage 1 or more according to Kellgren's osteoarthritic knee classification were selected randomly and analyzed radiologically. Eighty cases with the height of 155 cm-160 cm, for which a large number of male and female cases are available (34 male cases, 46 female cases) were extracted for analysis. The values measured were significantly larger in male than in female in any region. In order to clarify differences in morphology between the sexes, the ratio between the values measured of various regions was computed. As a result, the value obtained by dividing the length of medial femoral condyle in anterior-posterior direction and the depth of medial femoral condyle in proximal-distal direction by the width of femur at articular level was 0.87±0.03, 0.56±0.03 in female against 0.81±0.04, 0.52±0.03 in male, respectively. The value obtained by dividing the length of medial tibia condyle in anterior-posterior direction by the width of tibia at articular level was 0.61±0.05 in female against 0.59±0.04 in male. Anteversion of the femur in female was higher than that in male. When the differences between the sexes were studied, the values measured of various regions were significantly larger in males than in females even in the group of the same height. Morphologically, the knee of males tended to have a larger width than that of females

562 osteoarthritic knees rated as stage 1or more according to Kellgren’s osteoarthritic knee classification were selected randomly and analyzed radiologically. Eighty cases with the height of 155 cm-160 cm, for which a large number of male and female cases are available (34 male cases, 46 female cases) were extracted for analysis. The values measured were significantly larger in male than in female in any region. In order to clarify differences in morphology between the sexes, the ratio between the values measured of various regions was computed. As a result, the value(AP/ML ratio) obtained by dividing the length of medial femoral condyle in anterior-posterior direction and the depth of medial femoral condyle in proximal-distal direction by the width of femur at articular level was 0.87±0.03, 0.56±0.03 in female against 0.81±0.04, 0.52±0.03 in male, respectively. A statistically negative correlation was found between femoral width and AP/ML ratio. The value (AP/ML ratio) obtained by dividing the length of medial tibia condyle in anterior-posterior direction by the width of tibia at articular level was 0.61±0.05 in female against 0.59±0.04 in male. A statistically negative correlation was found between femoral width and AP/ML ratio. That is, the larger the medial-lateral width of the tibia becomes, the smaller becomes the AP/ML ratio. When the differences between the sexes were studied, the values measured of various regions were significantly larger in males than in females even in the group of the same height. Moreover, The AP/ML ratio of the current components does not follow the negative correlation between the width and AP/ML ratio. It was concluded that the size variation of the currently available components should be reconsidered

Single focal grade IV cartilage lesion in the knee has a poor healing capacity. Instead these lesions often progress to severe and generalized osteoarthritis that may result in total knee replacement. Current treatment modalities aim at biological repair and, although theoretically appealing, the newly formed tissue is at the best cartilage-like, often fibrous or fibrocartilaginous. This at the expense of sophisticated laboratory resources, delicate surgery and strict compliance from patients. An alternative may be small implants of biomaterial inserted to replace the damaged cartilage. We investigated the response of the opposing tibia cartilage to a metallic implant inserted at different depth into the surrounding cartilage level. Methods. The medial femoral condyle of both knees of 12 sheep, 70–90kg, 2 year of age and from the same breeder, was operated. A metallic implant with an articulating surface of 316L stainless steel, diameter of 7mm, HA plasma sprayed press-fit peg and a tailored radius and contour to the sheep femoral condyle was placed at the most weight-bearing position. The level of the implant was aimed flush, 0,3 and 0,8 mm below surrounding cartilage. The animals were stabled indoors, allowed to move freely and euthanized after 6 and 12 weeks. Postoperatively the knees were high resolution photographed for macroscopic evaluation. The position and depth of the implant were analysed using a laser scan device. Tibial and femoral condyles specimen were decalcified and slices were prepared for microscopic evaluation. Implant position and cartilage damage was assessed from two independent observers using a macroscopic ICRS score and a modified histologic score according to Mankin. Results. 22 tibia condyles showed a variety of cartilage damage ranging from severe damage down to subchondral bone to an almost pristine condition. There was a strong correlation between implant position and damage to opposing cartilage surface. Mankin score correlated significantly with implant position (p<0.001 regression analysis, r. 2. =.45) as did the ICRS score (p<0.001, regression analysis, r. 2. =.67). Implants sitting proud were associated with poor Mankin score. There was no difference between 6-week and 3-months knees. Conclusion. By precise postoperative measurement we have shown that significant imprecision occur; this has never before been studied. We found a distinct correlation between implant position and cartilage damage. These results suggest that further studies of metallic implants, inserted into cartilage defects with the utmost precision regarding the surrounding cartilage, may be warranted

Introduction. Unicompartmental arthroplasty is still a controversial issue in knee replacement, mainly due to a marked variation in published survival rates of the implants. The aim of this study was to analyse possible risk factors for revision following Oxford unicompartmental knee arthroplasties (OUKA). Material and methods. Since 1997 data for all patients with primary and revision knee arthroplasties performed in our department have been stored in a database. Selected for the present study was all primary OUKA performed in the period 1997–2006 as well as any revision following these operations until the end of 2008. We got information from The National Health Register and the CPR register about any revision performed at other institutions and date in case of death. Primary OUKA were grouped in three categories according to the experience of the surgeon: 1 for operation done by a surgeon who had performed less than 20 OUKA, 2 for operation by a surgeon who had performed 20–40, and 3 for operation by a surgeon who had performed more than 40. Risk of revision was analysed by Cox regression. Revisions due to pain as the only reason were excluded from the analyses. Age and gender of the patients, previous surgical intervention, operation time, and the experience of the surgeon were included as possible risk factors in the analysis. Results. 445 primary Oxford knee arthroplasties were included. These were followed by 46 revisions. The indications for the revisions were: aseptic loosening 16 knees, progression of the osteoarthritis to the lateral compartment 7 knees, dislocation of the polyethylene meniscus 5 knees, varus-valgus instability 3 knees, fracture of the medial tibia condyle 3 knees, collision of the polyethylene meniscus and the femur condyle 1 knee, and pain as the only reason 11 knees. Age and gender of the patients as well as previous surgical intervention in the knee in question were not correlated to the risk of revision. Operation time was correlated to risk of revision with decreasing risk with increasing operation time (p=0,001). The experience of the surgeon was also correlated to risk of revision with decreasing risk with increasing experience (p=0,02). The 6 years survival rate for an experienced surgeon using an operation time at 90 min. or more was 97,5 % compared to a survival rate at 78,7 % for an inexperienced surgeon with an operation time less than 90 min. Conclusion. OUKA performed by an inexperienced surgeon and OUKA performed with short operation time had marked reduced survival rates. This seems to be an essential information to institutions performing OUKA