Status and future of modern technologies in arthroplasty : Results of a survey of the German Society for Orthopedics and Trauma Surgery (DGOU).

BACKGROUND: The orthopedic community is divided on the question of whether modern technologies in arthroplasty improve outcomes. Therefore, the aim of this initiative of the working group on intraoperative imaging and technology integration (Arbeitsgemeinschaft intraoperative Bildgebung und Technologieintegration, AGiTEC) is to initiate the collection of additional data for the scientific evaluation of modern technologies. QUESTION: To what extent are modern technologies currently used and which implementations are planned? Do the members of the German Society for Orthopedics and Trauma Surgery (DGOU) consider the acquisition of additional data for scientific assessment necessary? METHODS: Members of the DGOU were asked via an e­mail survey about the distribution and projected introduction of modern technologies in arthroplasty. They were also asked whether sufficient data were collected for scientific evaluation and whether acquisition of additional data in studies or arthroplasty registries were considered necessary. RESULTS: Of the 7923 probands surveyed, 428 completed the questionnaire in full (5.4%). It was found that individual implants and navigation are currently the most frequently used (31% and 29%, respectively). The largest increases in the next 2 years are projected for virtual reality and robotics (+30% and +23%, respectively), 85% of respondents indicated that insufficient data were collected for scientific evaluation, and 89% each requested initiation of multicenter studies and inclusion of technologies in the arthroplasty registry. CONCLUSION: The results of this study should motivate the scientific community, industry, and those responsible for the arthroplasty registries to collect and analyze data for the scientific assessment of modern technologies.

Articulating spacers compared to fixed spacers for the treatment of infected knee arthroplasty: A follow-up of 37 cases.

BACKGROUND: The standard treatment of a periprosthetic infection after TKA involves a two-stage reimplantation with the intermittent implantation of spacers. Different designs of spacers have been described; currently articulating spacers and fixed spacers are used. The aim of the present study is to compare the advantages/disadvantages of the different spacers. PATIENTS AND METHODS: In this retrospective study we analyzed 37 cases after revision surgery of infected TKA. All patients that received spacers as part of the two-stage reimplantation were included. Exclusion criteria were massive bone loss prior to revision, because the implantation of a mobile spacer would not have been possible. RESULTS: The average ROM was 98.0 (± 14.9) degrees in the articulating spacer group (group 1) and 79.3 (± 22.5) in the group that received the fixed spacers (group 2) before revision surgery started. At a late follow up the average ROM for group 1 was 102.0 (± 8.4) and 79.0 (± 26) for group 2. CONCLUSION: The use of articulating spacers in the two-stage revision for infected total knee arthroplasty is a safe alternative to fixed spacers, that equally preserves ligament balancing and has equal infection eradication rates. A long term improvement of the range of motion following reimplantation of the new joint was, however, not observed.

[Total knee arthroplasty with the use of patient specific instruments. The VISIONAIRE system]. / Knietotalendoprothetik mithilfe patientenspezifischer Instrumente. Das VISIONAIRE-System.

BACKGROUND: Accurate component positioning and correct post-operative whole-leg alignment are crucial for ensuring the optimal long-term performance of a knee replacement. Patient-specific instrumentation (PSI) was introduced in an attempt to reduce outliers in the positioning of components and in the alignment of the leg axis in comparison with conventional techniques. METHODS AND RESULTS: A review of our own investigations and studies by other groups, it has been shown that PSI could reduce the amount of outliers in the positioning of tibial and femoral components and in whole-leg alignment. In this way, PSI differs from other procedures for improving component placement, such as navigation, for which no advantage could be demonstrated, especially with regard to rotation in comparison with conventional techniques. In this publication we focus on the VISIONAIRE PSI system (Smith&Nephew). In addition, the efficiency aspects of PSI are discussed, which differ from the conventional method because of the use of disposable instruments.

Can CT-based patient-matched instrumentation achieve consistent rotational alignment in knee arthroplasty?

PURPOSE: Long-term success of contemporary total knee replacements relies to a large extent on proper implant alignment. This study was undertaken to test whether specimen-matched cutting blocks based on computed axial tomography (CT) scans could provide accurate rotational alignment of the femoral component. METHODS: CT scans of five fresh frozen full leg cadaver specimens, equipped with infrared reflective markers, were used to produce a specimen-matched femoral cutting block. Using those blocks, the bone cuts were made to implant a bi-compartmental femoral component. Rotational alignment of the components in the horizontal plane was determined using an optical measurement system and compared with all relevant rotational reference axes identified on the CT scans. RESULTS: Average rotational alignment for the bi-compartmental component in the horizontal plane was 1.9° (range 0°-6.3°; standard deviation 2.6°). One specimen that showed the highest deviation from the planned alignment also featured a completely degraded medial articular surface. CONCLUSIONS: The CT-based specimen-matched cutting blocks achieved good rotational alignment accuracy except for one specimen with badly damaged cartilage. In such cases, imaging techniques that visualize the cartilage layer might be more suitable to design cutting blocks, as they will provide a better fit and increased surface support.

Expression of vascular endothelial growth factor on chondrocytes increases with osteoarthritis - an animal experimental investigation.

OBJECTIVE: To evaluate the expression of VEGF by chondrocytes of hyaline cartilage during the course of osteoarthritis (OA). METHODS: In 12 white New Zealand rabbits the anterior cruciate ligament (ACL) was resected to create an anterior instability of the knee. In 12 control rabbits only a sham operation without resection of the ACL was done. Four animals of each group were killed at 3, 6, and 12 weeks. The load bearing area was evaluated histologically according to Mankin and by immunostaining for VEGF. RESULTS: In the experimental group, histological grades of OA showed a positive linear correlation with the time after surgery. Immunostaining showed an increased expression of VEGF in the control group after 3 weeks, which dropped to normal after 6 weeks. There was no difference in the progression of OA between control and experimental groups after 3 weeks, but a significant difference was seen after 6 (p=0,01) and 12 (p=0,05) weeks. A significant positive correlation between VEGF expression and the histological grade of OA was found (r = 0.767; p<0.01). CONCLUSIONS: An increase of VEGF expressing chondrocytes occurs during time course of OA.

[Reliability of static posturography in elderly persons]. / Reliabilität der statischen Posturografie bei älteren Personen.

BACKGROUND AND OBJECTIVE: Static posturography is used to quantify body sway. It is used to assess the balance of elderly persons who are prone to falls. There is still no general opinion concerning the reliability of force platform measurements. The aim of this study was to test the reliability of force platform parameters when measuring elderly persons. PROBANDS AND METHODS: The reliability of 11 force platform parameters was tested measuring 30 elderly persons. The following parameters were calculated: mean speed of center of pressure displacement in mm/s, length of sway in mm, sway area in mm(2), amplitudes of center of pressure movement, the axis of oscillation in degrees and the person's angles of inclination in degrees. Three measurements were taken on the same day, with a resting period of 2 min. Four different test conditions were used: normal standing and narrow stand with eyes open and eyes closed, respectively. Reliability was determined by using intraclass correlation coefficients. RESULTS: Six parameters had excellent reliability with a correlation coefficient of >0.9: mean speed of center of pressure movement during narrow stand, area of sway during narrow stand, length of sway during normal and narrow stand, and the angle of inclination in the sagittal plane during normal stand and narrow stand. The condition "narrow stand eyes closed" proved to be the most reliable test position. CONCLUSION: Six parameters proved to have excellent reliability and are recommended to be used in further investigations. Narrow stand with eyes closed should be used as the test position. The tested protocol proved to be reliable. Whether these parameters can be used to predict falls in elderly persons remains to be investigated.

Primary stability of tibial components in TKA: in vitro comparison of two cementing techniques.

In spite of improvements in cementing technique, migration of tibial component remains a problem in total knee arthroplasty. This study compares the primary stability of tibial components using two different cementing techniques with roentgen stereophotogrammetric analysis (RSA) in vitro. A total of 20 tibia specimens were matched into two groups, 10 specimens per group. Cementing technique was randomized to each group. In the first group only the base and in the second group the base and stem were cemented. The implants and the tibial metaphysis were marked with markers for the RSA analysis. All specimens were tested with an axial load of 2,000 N for 1,000 and 10,000 cycles and RSA analysis was performed. Endpoints for radiosterometric analysis were maximum total point motion, maximum subsidence, lift off, rotation and translation along the x-, y-, and z-axes. After 1,000 and 10,000 cycles, no significant differences could be found, but two tibial components of the surface cementing group showed a migration of more than 2 mm defined as failure compared to six failed tibial components in the full cementing group (P = 0.068). This higher number of failed arthroplasties in the fully cemented prosthesis group demonstrates a disadvantageous load distribution in the tibia apophysis which can cause an early component loosening.

[Comparison of medium-term clinical and radiological outcome between cemented and cementless medial unicompartmental knee arthroplasty]. / Mittelfristiger, klinischer und radiologischer Vergleich von zementierten und zementfreien, medialen, unikompartimentellen Knieendoprothesen.

AIM: Cementation of tibial implants in total knee arthroplasty is the gold standard considering the high loosening rates of cementless implants. In contrast, only sparse data exist regarding unicondylar arthroplasty due to its lesser use. In this study, we compare cemented with cementless unicondylar knee arthroplasty and aim to define both clinical and radiological differences in treatment outcome. MATERIALS AND METHODS: In a retrospective study, 106 patients who had undergone a medial unicondylar replacement were examined after a mean postoperative period of 8 years. Of these, 42 patients (median age 81 +/- 7 years) had received a cemented and 64 (median age 73 +/- 7 years) a cementless knee arthroplasty by the same surgeon while 7 patients were deceased or could not be reached. Well-established clinical (VAS, HSS, KSS, UCLA, WOMAC) and quality of life (SF-36) scores were used to evaluate treatment outcome. X-rays were performed to evaluate periprosthetic loosening zones, according to Ewald's criteria. RESULTS: The cementless patient group presented significantly better clinical scores (HSS, KSS, UCLA, WOMAC), except in the visual analogue scale (VAS) for pain assessment. The quality of life was significantly better in the cementless group except in the subgroups for physical function, vitality and social role, in that it resembles the normal population. Moreover, radiographic analysis using antero-posterior X-rays revealed significantly more and larger periprosthetic loosening areas in tibial zone 2 in the cementless group. CONCLUSION: The inferior clinical results characterising the cemented group could be attributed to the higher mean age. Regarding the radiological loosening zones, we did not detect any differences in the techniques of fixation, although physical activity and accordingly mechanical stresses were higher in the cementless group.

Gait patterns after intraarticular treatment of patients with osteoarthritis of the knee--hyaluronan versus triamcinolone: a prospective, randomized, doubleblind, monocentric study.

OBJECTIVE: Evaluation of gait performance and muscle activity patterns as well as clinical efficacy and safety after single intraarticular injection with hyaluronan compared with triamcinolone in patients with knee osteoarthritis. MATERIALS AND METHODS: This trial evaluated the influence of a single injection of hyaluronan or triamcinolone on gait pattern and muscle activity. For clinical evaluation a visual analogue scale for pain, Lequesne index, and Knee Society Score were used. Quality of life was assessed with the SF-36. RESULTS: The complete analysis was performed in 50 of 60 patients. 26 patients were treated with triamcinolone and 24 with hyaluronan. Hyaluronan treatment led to significant improvement of range of motion at hip and knee. Significant improvement could be either demonstrated for the pain scale, Lequesne and Knee Society score in both groups. Quality of life showed greater improvement in the triamcinolone group. CONCLUSION: Single application of high-viscosity hyaluronan shows superior range of motion and pain reduction as well as improvement in clinical results. Even if there was a lack of significant differences compared to triamcinolone, this therapy classified as safe and effective in the short follow up.

[Patellofemoral arthroplasty--results of a nation-wide survey in Germany and review of the literature]. / Patellofemorale Endoprothetik in Deutschland - eine Standortbestimmung und Uberblick über die Literatur.

BACKGROUND: Isolated patellofemoral arthroplasty is discussed controversially. The aim of this nation-wide survey in Germany and review of the literature was to determine the current status of patellofemoral arthroplasty. METHODS: A standardised questionnaire was sent to 744 German departments of orthopaedic surgery, traumatology and general surgery. In the first part, surgeons were asked general questions about their department size, case numbers of knee arthroplasties per year and non-endoprosthetic treatment of isolated patellofemoral disorders. If patellofemoral arthroplasty was conducted, parameters concerning age, gender, duration of complaints, indication for surgery, surgical approach, type of endoprosthesis used, additional surgical treatments and failures were evaluated in the second part. Furthermore we asked for the reasons if no isolated patellofemoral arthroplasty was performed. A systematic review of the literature was done including studies published until October 2007. The main inclusion criterion was the presentation of results after the implantation of a patellofemoral prosthesis for isolated patellofemoral osteoarthritis. RESULTS: A total of 225 analysable questionnaires were returned. Of 53,420 knee arthroplasties performed per year, only 195 (0.37 %) were isolated patellofemoral arthroplasties. The majority of patients (91 %) were between 40 and 80 years old. The aetiology of isolated patellofemoral osteoarthritis was believed to be idiopathic in 41 % and traumatic in 8 %. Patellofemoral dysplasia was held to be responsible in 47 % and patellofemoral instability in 4 % of the cases. The main reason for failure and surgical revision was ongoing tibiofemoral osteoarthritis of the affected knee. Negative attitude and disbelief towards the success of isolated patellofemoral arthroplasty were stated by the majority (62 %) of non-users. A lack of appropriate indications was reported by 22 % and lacking know-how by 16 %. We analysed 12 studies (459 implantations; 390 patients) in the literature review. The treatment was considered successful in 67.8 % of cases. The overall revision rate was 30.3 %. The highest failure rates were in patients with progression of tibiofemoral osteoarthritis or malalignment. CONCLUSIONS: Isolated patellofemoral arthroplasty has only low significance among surgeons performing knee arthroplasty in Germany. The majority of surgeons do not believe in the success of the procedure. Almost one third of published cases in the literature needed to be revised.

[The influence of cryotherapy of the ankle on static balance]. / Der Einfluss der Kryotherapie am Sprunggelenk auf das statische Gleichgewicht.

AIM: The ankle is one of the most often injured joints. About it, poor balance which for example was identified on the basis of an increased sway of the centre of pressure (CoP) while it was measured with force plates is said to be an important risk factor. In the treatment of acute distorsion, ice is recommended after the trauma and in rehabilitation ice is supposed to further the beginning of active exercise and its progression. In practice it can happen that sportsmen are sent back to training or competition directly after cryotherapy. Although the question is controversially discussed, if physical activities can be re-established without danger or if an increased susceptibility to injury exists after ice application. This investigation takes up the problems if ice application at the ankle disturbs static balance so that an enlarged risk of injury could result. METHOD: In a prospective, controlled crossover study the body sway of 31 healthy subjects (19 women and 12 men, 31 +/- 5 years old with a body height of 1.72 +/- 0.1m and a body weight of 68.13 +/- 11.96 kg) before and after a ten minutes ice application at the ankle (ice) or rather before and after a ten minutes rest without any treatment (con) were analysed. The measurements took place during a 30 seconds single leg stance on a PDM multifunction force plate. The sequence, whether the investigation should first been performed with or without ice application, was allocated randomly. RESULTS AND CONCLUSION: Within the bounds of this study and its restrictions a ten minutes ice application of the ankle did not disturb the static balance in single leg stance and does not hold any enlarged susceptibility to injury with regard to this risk factor. Conclusions about the effect on other risk factors for ankle injury can not be drawn from this study and require independent investigations.

Expression of the matrix receptor CD44v5 on chondrocytes changes with osteoarthritis: an experimental investigation in the rabbit.

OBJECTIVE: To evaluate the expression of CD44v5 on chondrocytes of hyaline cartilage during the course of osteoarthritis (OA). METHODS: In 12 white New Zealand rabbits the anterior cruciate ligament (ACL) was resected to create an anterior instability of the knee. In 12 control rabbits only a sham operation without resection of the ACL was done. Four animals of each group were killed at 3, 6, and 12 weeks. The loadbearing area was evaluated histologically according to Mankin and by immunostaining for CD44v5. RESULTS: In the trial group, histological grades of OA showed a positive linear correlation with the time after surgery. Immunostaining showed an increased expression of CD44v5 in the control group after 3 and 6 weeks, which dropped to normal after 12 weeks. There was no difference between control and trial groups after 3 and 6 weeks, but a difference was seen after 12 weeks. A significant positive correlation between CD44v5 expression and the histological grade of OA was found (r = 0.314). CONCLUSIONS: An in vivo increase of expression of the hyaluronan receptor CD44v5 occurs during the course of OA. Further studies are needed to evaluate whether this pattern applies to man and whether new treatment approaches might evolve from this knowledge.

[Patellar instability]. / Femoropatellare Instabilität.

We report a retrospective study of patients with patellar instability, all treated by operation and followed up for 3 years. Patients with recurrent dislocation of the patella, lateral displacement and primary patella dislocation were treated by a Elmslie-Trillat reconstruction combined with a soft tissue intervention. Preoperative and follow-up radiographic evaluation included weight bearing anteroposterior view and merchant view. Evaluation was done using the Insall-Salvati index, sulcus and congruence angle. The operation was performed on 23 patients. The clinical evaluation at follow-up was performed using the Knee-Society- and Tegner-Score. Subjective results of the operation were excellent or good in 22 of the 23 at three years with a redislocation rate of only 1 out of 26. Most patients were able to return to the same level of sporting activity as before the injury. The technique described in this paper tries to correct as much as possible of the abnormal parameters in patellar instability to achieve a dynamic stability of the patella through the full range of motion. The excellent results are presumable explained by the use of the combined technique.

[Jumper's knee--a review]. / Jumper's knee -- eine Ubersicht.

Jumper's knee has been defined as painful chronic overuse injury of the extensor mechanism of the knee joint. The disease has a high incidence in jumping sports and depends on training frequency and level of performance. Its natural course is protracted, repetitive, and often bilaterally occurring. Its etiology is a chronic overload of the knee extensor mechanism which is triggered by jumping sports (volleyball, basketball etc.) as well as different intrinsic (ligamentous laxity, Q-angle, patella height, tenderness, pattern of force development) and extrinsic dispositions (frequency of training, level of performance, hardness of underground). The place of pathology most often is the osteo-tendinous transition zone of the proximal patellar tendon. Histologic evaluation of the tendon showed that the disease is rather degenerative than inflammatory. The diagnosis is primarily based on the typical sports history, physical examination, and ultrasound. MRI is helpful in operation planning. Plain radiography, CT, and bone scans are used to rule out differential diagnoses. Therapy should be chosen according to the stage of the disease and usually starts with a non-surgical approach. This includes rest from sports activities, immobilisation, non-steroid antiphlogistics, para-tendinous cortisone injections, massage, electric therapy, ultrasound and extracorporal shock waves. Afterwards an increase of activities is begun (moderate training, adequate warm-up, ice cooling after activity, muscle stretching, eccentric strengthening of the quadriceps). Patella straps and soft insoles are used as prevention. Up to 42 % of patients need surgical therapy after failure of long-lasting non-surgical measures, carried out either open or arthroscopically. Surgical principles include excision of the para-tendon, excision of the degenerative tissue, resection of the lower patella pole, and longitudinal incisions into the tendon. Most patients are pain-free after surgery but return to sports only at a lower level.

Clinical and functional comparison of uni- and bicondylar sledge prostheses.

The aim of the present study was the evaluation of differences in clinical results, proprioceptive performance and gait in patients with unicondylar and bicondylar sledge prostheses of the knee. In a retrospective study, 17 patients with unicondylar sledge prostheses were compared with 15 patients with bicondylar sledge prostheses. Clinical examination was rated using HSS, Knee Society, and patellar scores and a visual analogue scale for pain. Proprioceptive performance was examined using sway measurements during single leg stance on a force platform. In addition, the patients underwent 3-D gait analysis including measurements of ground reaction forces and surface electromyographic (EMG) investigation of the lower extremity. Comparing both patient groups in clinical scores, gait, EMG and proprioception, no significant differences were found. Implantation of bicondylar sledge prostheses retaining both cruciate ligaments achieves functional results as good as unicompartmental arthroplasty. The presented results might encourage future research on new models of total joint replacement with preservation of both cruciate ligaments.

Hyaline cartilage degenerates after autologous osteochondral transplantation.

OBJECTIVES: Autologous osteochondral grafting is a well-established clinical procedure to treat focal cartilage defects in patients, although basic research on this topic remains sparse. The aim of the current study was to evaluate (1) histological changes of transplanted hyaline cartilage of osteochondral grafts and (2) the tissue that connects the transplanted cartilage with the adjacent cartilage in a sheep model. METHOD: Both knee joints of four sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral femoral condyle. The animals were sacrificed after three months and the received knee joints were evaluated histologically. RESULTS: Histological evaluation showed a complete ingrowth of the osseous part of the osteochondral grafts. A healing or ingrowth at the level of the cartilage could not be observed. Histological evaluation of the transplanted grafts according to Mankin revealed significantly more and more severe signs of degeneration than the adjacent cartilage, such as cloning of chondrocytes and irregularities of the articular surface. CONCLUSION: We found no connecting tissue between the transplanted and the adjacent cartilage and histological signs of degeneration of the transplanted hyaline cartilage. In the light of these findings, long-term results of autologous osteochondral grafts in human beings have to be followed critically.

Muscle strength in patients with unicompartmental arthroplasty.

OBJECTIVE: The aim of the current study was to evaluate the isokinetic strength of the knee in patients with unicondylar prostheses, to compare these results with healthy control subjects of the same age, and to correlate these results with clinical scores. DESIGN: Seventeen patients were examined an average of 21.5 mos after surgery. Clinical examination was done using the Hospital for Special Surgery, Knee Society, and patellar scores and a visual analog scale for pain. Quality of life was assessed by the Short Form 36 Health Questionnaire. Isokinetic evaluation of knee extensor and flexor muscles was done using a Cybex 6000 dynamometer at angular velocities of 60 and 180 degrees/sec. Eleven healthy subjects of comparable age served as a control group. RESULTS: Clinical results differed significantly in all categories. Quality of life differed only in the items of physical functioning, role limitation because of physical problems, and bodily pain. Isokinetic strength in patients showed a loss of torque of approximately 30% in extension and flexion at 60 and 180 degrees/sec compared with the control group. The flexion and extension ratio and the angles of maximum torque did not differ between the groups. CONCLUSION: In comparison with healthy control subjects, persons with an implanted unilateral sledge prosthesis have strength deficits in extension and flexion. A deficit of the extensor muscles, as it has been described previously for patients with a total knee arthroplasty, could not be found.

[MRI evaluation of meniscal movement and deformation in vivo under load bearing condition]. / Kernspintomographische Untersuchung der Meniskusbeweglichkeit und -deformation in vivo unter Gewichtsbelastung.

AIM: The aim of this experimental study was a quantitative evaluation of meniscal movement and deformation in vivo under load bearing conditions. METHODS: Sagittal T1-weighted MRI pictures of 15 healty knees were evaluated. The subjects were placed in an open MRI, that enabled measurements under load bearing and in different flexion grades. Series of pictures of the medial and lateral meniscus without load, with half and full body weight load and in full extension and 30 degrees flexion were taken. Two examiners measured twice the height of the posterior horn, and the inner and outer distance between the anterior and posterior horns of the menisci. RESULTS: The height of the posterior horns of the medial and lateral menisci decreased with increasing load. The inner and outer distance increased with load, the inner distance more than the outer, resulting in a compression of the periphery. Increase of flexion from 0 degrees to 30 degrees significantly influenced only the outer distance of both menisci. CONCLUSION: This method can be used in future to functionally evaluate the postoperative result after meniscus saving or replacing therapies. The compression of meniscal periphery from the inside to the outside under load in full extension allows early postoperative mobilisation after meniscal sutures.

Clinical and functional comparison of bicondylar sledge prostheses retaining all ligaments and constrained total knee replacement.

OBJECTIVE: Comparison of different total knee replacements regarding clinical and functional differences with respect to gait and electromyographic analyses. DESIGN: Retrospective, comparative, clinical and functional study. METHODS: Three groups (control group of 11 healthy subjects, 15 patients with bicondylar sledge prostheses retaining all ligaments (cemented unicondylar prostheses in both the medial and lateral compartment), 15 patients with constrained total knee replacement sacrificing all cruciate and collateral ligaments (cemented total knee prosthesis with intramedullary stems and a large intercondylar tibial post) were compared by clinical evaluation using a number of clinical evaluation scores, a pain scale, surface electromyographic examinations of the lower limb, and gait analysis. RESULTS: Clinical scores revealed significantly worse results for patients with constrained prostheses. Both patient groups had significantly lower clinical scores compared to the control group. Gait analysis and electromyographic parameters revealed no significant differences between both patient groups. Compared to the control group, patients revealed significantly impaired parameters. Electromyography also demonstrated significant differences between patients and controls: mean electromyographic activities were reduced in vastus medialis and lateralis, semitendinosus, tibialis anterior and gastrocnemius. Peak activities were reduced in all muscles but rectus femoris. CONCLUSION: Clinical scores demonstrated significantly better results in bicondylar sledge than in constrained prostheses. Nevertheless, gait and electromyographic analyses did not reveal significant differences. RELEVANCE: Retaining of ligaments in bicondylar sledge prostheses apparently improved the activities of daily living but is not reflected in gait and electromyographic parameters.

CD44H and the isoforms CD44v5 and CD44v6 in the synovial fluid of the osteoarthritic human knee joint.

OBJECTIVE: To determine whether the concentrations of CD44H and v5 and v6 in the synovial fluid are correlated with the presence of accompanying synovitis in the osteoarthritic joint and with the grade of osteoarthritis. DESIGN: Using antero-posterior and lateral X-rays of the knee joint and patellar view of 46 patients were graded with the Kellgren & Lawrence scale. Synovial fluid from these patients with different grades of primary osteoarthritis of the knee joint with and without synovial inflammation (synovitis) was collected during surgical procedures. A horseradish peroxidase conjugated anti-CD44H-, anti-sCD44v5- or anti-sCD44v6-antibody was added and labeled with tetramethylbenzidine. The absorbance was measured at wavelengths of 450/620 nm. Regression analysis was performed and the statistical significance was assessed, using the Student t-test for unequal variance. RESULTS: CD44H and v5 and v6 were detected in the synovial fluid of all 46 patients. Osteoarthritic patients with synovial inflammation showed significantly higher levels of CD44H and v6, but not v5, than osteoarthritic patients without synovial inflammation. With progression of osteoarthritis from Kellgren grade II to III, CD44v5 decreased significantly. All other isoform concentrations remained statistically unchanged. CONCLUSIONS: CD44H and the isoforms v5 and v6 were present in the synovial fluid of osteoarthritic patients. Their concentrations do not reflect the osteoarthritic stage in the Kellgren grading scale. CD44H and CD44v6, but not CD44v5, are significantly up-regulated in osteoarthritic synovial inflammation.