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Background: Juvenile osteochondritis dissecans of the knee joint is the most common osteochondral lesion during growth, usually occurring between the 10th and 14th year of age., Pathogenesis: Repetitive microtraumata lead to a subchondral osseus lesion, which is commonly located at the medial aspect of the femoral condyle. Sport activities are considered to be the main cause, although genetic and hereditary factors as well as vitamin D 3 deficiency also play a role. Current classification systems distinguish between stable and unstable osteochondral lesions, which is decisive for further treatment., Treatment: Stable lesions may heal through conservative treatment by avoiding weight bearing and sport. Unstable lesions, on the other hand, can lead to a complete defect of the joint surface with the formation of a free joint body. In such cases, various surgical techniques aim at reconstructing the surface of the joint, in order to reduce the risk of secondary arthritis., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Objective: The aim of arthroscopically assisted treatment of tibial plateau fractures is to achieve minimally invasive reduction and internal fixation of the joint fracture of the tibial plateau. Using the arthroscopic procedure, both the approach morbidity and the control of the articular reduction can be optimized., Indications: Displaced tibia plateau fractures of AO type A1 and B1/2/3 or Tscherne P2., Contraindications: Strongly displaced tibial plateau fractures, which require an open surgical approach and stabilization with plate fixation (e.g., AO type C fractures or Moore type 5 fractures); 2nd and 3rd degree open fractures. Danger of compartment syndrome., Surgical Technique: Planning of the surgical approach and confirmation of the indication by CT imaging. Diagnostic arthroscopy of the knee joint with treatment of associated injuries and confirming the indications for arthroscopically assisted reduction. Under arthroscopic control, insertion of an ACL tibial aiming device. In the central portion of the dislocated fracture fragment, a 2.4 mm K-wire is placed with the help of the aiming device. Opening of the outer cortex using a cannulated drill (9-11 mm diameter), introduction of a cannulated plunger below the fracture resulting in reduction of the fracture and compression of the cancellous bone below the fracture. Simultaneously the reduction is controlled by arthroscopy. Finally, the fracture is fixed using minimally invasive screw fixation (3.5-7.3 mm cancellous screws with washers) or by plate osteosynthesis (e.g., support plate). The metaphyseal defect can optionally be filled with bone substitute material., Postoperative Management: Rehabilitation is dependent on the extent of the fracture. In arthroscopically treated fractures, partial weight bearing of 20 kg over a period of 6-12 weeks is usually necessary.

In addition to ultrasound and conventional x-ray, magnetic resonance imaging (MRI) plays an important role in the visualization of lesions of the knee. It allows the orthopaedic surgeon to safely detect ruptures of the cruciate ligaments, the meniscus, osteochondral lesions and other ligamentary structures such as the collateral ligaments and the medial patellofemoral ligament (MPFL). In patellar dislocations, risk factors for recurrent dislocations can be determined and the therapy can be adjusted accordingly.This articles aims to give the reader a comprehensive overview on current concepts and techniques in the use of MRI for lesions of the knee. It focuses on patellar dislocations, where MRI plays a dominant role in supporting decision making for the best therapeutic strategy.

Objective: Reconstruction of knee stability by primary ligament sutures and additional augmentation after knee dislocation., Indications: Acute knee dislocation Schenck type III and IV. Operative treatment should be performed within 7 days after injury., Contraindications: Chronic instability after knee dislocation, refixable bony avulsions, critical soft tissue, infection, lack of compliance., Surgical Technique: Supine position with electric leg holder. Short arthroscopic assessment of concomitant injuries. Schenck type III medial injuries and Schenck IV injuries: anteromedial parapatellar arthrotomy. Injuries type Schenck III lateral: anteromedian arthrotomy. Armoring of ligament stumps for transosseus sutures. Placement of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) drill tunnels. Extracortical diversion of the suture armorings and insertion of augmentation systems. Fixation of the PCL augmentation in 70-90° flexion. Fixation of the ACL augmentation in 20-30° flexion. Knotting of the transosseus ligament sutures. If necessary (postero-)lateral and/or medial stabilization., Postoperative Management: Limited weight bearing with 20 kg for 6 weeks. Stabilizing brace (e.g., Hypex-Lite®, Albrecht) generally for 12 weeks. Mobilization under tension of the quadriceps muscle for 6 weeks., Results: In total, 20 patients have been treated using the principle of "ligament bracing". So far 8 patients (aged 18-60 years, median 33 years) have been assessed with a follow-up of 10-15 months (median 12 months) postoperatively. In all, 6 patients showed stable knees with good results. Recurrent instability of the ACL was observed in 2 patients; the collateral ligaments and PCL were stable. For the evaluation the following scores were used: IKDC score, Tegner score, and Lysholm score. To objectify the data, stress radiography and physical examination were performed. Using the operative technique mentioned above, no complications occurred. During follow-up 2 patients reported a deficiency of flexion.

Patellar dislocation is the lateral displacement of the patella from the femoral trochlea. Affected individuals typically have underlying anatomic risk factors of variable magnitude, which, in conjunction with leg rotation, cause the event. Magnetic resonance imaging (MRI) permits straightforward diagnosis of the typical features of recent patellar dislocation: contusion edema of the inferomedial patella and the lateral femoral condyle as well as rupture of the medial patellofemoral ligament. In case of concomitant osteochondral injury, early surgical refixation may be indicated, depending on the size. After a first dislocation, which can damage the capsuloligamentous stabilizers, subjects may sustain further dislocations or even develop chronic patellofemoral instability, depending on the presence and severity of anatomic variants. A wide range of conservative and surgical treatments are available. While a first patellar dislocation is often treated conservatively, surgical strategies after a second dislocation depend on the pattern of injury and the severity of underlying anatomic risk factors. The most relevant predisposing variants are trochlear dysplasia, patella alta, and an abnormal tibial tubercle to trochlear groove distance (TT-TG). The radiologist's report should give a quantitative estimate of both the injuries resulting from dislocation and the underlying anatomic risk factors. An accurate characterization of the individual pathomechanism is crucial for tailoring treatment., (© Georg Thieme Verlag KG Stuttgart · New York.)

Aim: This study was aimed to evaluate the correlation between sports activity and frequency and grad of non-traumatic knee cartilage lesions., Methods: A total of 868 patients (469 male and 399 female) who were suffering from knee pain (> 3 months) had undergone knee arthroscopy. The mean duration of history was 11.4 ± 11.5 (3 - 48) months. Criteria for exclusion were major knee injuries (e. g., ACL injuries). All cartilage lesions were classified according to the ICRS (International Cartilage Repair Society) guidelines and summarised with the semiquantitative WOAKS (Whole Organ Arthroscopic Knee Score)., Results: There was a significant correlation between cartilage degeneration and age. Older female patients (63 to 85 years) demonstrated higher knee degenerations than male patients. The grade cartilage degeneration was higher in non-sportspersons (WOAKS = 13.5 ± 13.8) than in sportspersons (WOAKS = 7.1 ± 5.3), p < 0.001. Only in younger patients (17 to 34 years) was there no difference in the frequency of cartilage lesions in correlation to sports activity. A high-pivoting sport was significantly more frequently associated with cartilage degeneration in comparison to low-pivoting sports. Cartilage lesions most frequently occur within the mean bearing zones of the medial knee compartment. With regard to sports activity, no differences were observed in the distribution of cartilage lesions., Conclusions: Sportspersons who suffer from knee pain without injury have significantly less cartilage lesions or, respectively, severe cartilage defects. Cartilage lesions mostly occur within the medial knee compartment without correlation to sports activity and sport type. Patients who are performing "high-pivoting" sports more frequently are suffering from severe cartilage lesions than "low-pivoting" sportspersons. For a final epidemiological estimation of any correlations between sports and cartilage damage, longitudinal MRI studies are needed., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: Meniscal degeneration (MD) is a structural change of fibrous cartilage that is common in orthopaedic diagnostics and relevant for health insurance matters. So far, there has been neither a standardised scoring system nor an immunohistochemical marker for MD., Material and Method: In this retrospective trial, the meniscal tissue of 60 patients was assessed immunohistochemically for NITEGE (G1 fragment of the proteoglycan aggrecan) expression. NITEGE expression was correlated with defined grades of MD: little (grade 0/1), medium (grade 2), or severe (grade 3)., Results: Detection of extracellular NITEGE deposits in grade 2 or 3 MD had a positive predictive value and specificity of 100%, whereas no deposits were found in grade 0/1 MD. Sensitivity in advanced MD was 55%. Detection of extracellular NITEGE correlated positively with the grade of degeneration, as did patient age and the grade of degeneration. The patient age of those with grade 0/1 MD was significantly lower than for grade 3 (p<0.0001)., Conclusion: The thoroughly defined degeneration score (grade 1 - grade 3 MD) is suitable to assess the severity of degeneration. Extracellular NITEGE deposits can be regarded as an immunohistochemical marker for advanced (grades 2 and 3) MD.

Complex knee ligament injuries are characterized by simultaneous rupture of the anterior cruciate ligament (ACL) and/or the posterior cruciate ligament (PCL) and at least one collateral ligament. Isolated injury to the medial collateral ligament (MCL) and PCL have a high healing capacity and can be treated conservatively in many cases. Ruptures of the MCL can also be treated conservatively in complex injuries if the cruciate ligaments are reconstructed. Ruptures of the lateral structures usually need surgical reconstruction. Indications for acute surgical repair include meniscus dislocation, entrapment of collateral ligament portions in the joint, knee dislocation with severe knee instability, and displaced bony avulsions. The anatomy of the knee ligaments must be carefully respected in surgical reconstruction. Acute repair of collateral ligament injuries is possible only in the first 2 weeks after trauma. Acute arthroscopy is indicated only in combination with reconstructive surgery.

Menisci fulfill many functions within the complex biomechanics of the knee joint. In the case of meniscus lesions, sparing arthroscopic resections and operative refixation are the treatments of choice. With regard to diagnostics, this means that in general terms, the histopathologic diagnostics are carried out on detached meniscus fragments of between 5 mm and 2 cm in size. An experienced pathologist's knowledge of physiologically possible cellular and fibrous histological meniscus damage, as opposed to nonphysiological change regarded as normal with respect to age, is essential during a diagnostic meniscus evaluation. The clinician expects clear statements from the pathologist regarding the severity of previous or secondary degenerative meniscus damage, the age and type of traumatic tears, and appraisal of the relationship between trauma and meniscus damage from an insurance point of view. Close cooperation between the clinician and the pathologist allows for fast and unambiguous correlation of anamnesis, the clinical picture, and morphological reporting so that cases involving insurance problems - which are numerous, often long-term, and often unsatisfactory - can be clarified quickly.

The synovial membrane is a site where many diseases with different etiologies can become manifest. Tumors and storage diseases are some of the rare conditions, whereas crystal deposition diseases, acute bacterial infections and in particular chronic uncharacteristic synovitis are frequently encountered. The latter present a diagnostic problem, because they can barely be assigned to concrete diagnoses. This report will give an overview of the differential diagnosis of joint diseases and will focus on the so-called synovitis score as a tool for the systematic evaluation of chronic uncharacteristic synovitis, providing a possibility to differentiate between degenerative and rheumatic synovitis with a specificity of 60.5% and a sensitivity of 95.5%.

Aim: Have chondral lesions been found in the course of an articular injury? Are these lesions of traumatic or degenerative origin? Is it possible to differentiate traumatic from pre-existing pathology with the help of history, clinical findings and imaging features? The answers to these questions are of paramount importance in the setting of legal expert assessment., Method: The diagnosis of an acute traumatic chondral injury is based on arthroscopic and/or MRI findings. MRI is the diagnostic method of choice in a suspected isolated chondral injury., Results: The method yields high accuracy in detecting chondral and osteochondral lesions. The MRI finding of a concomitant subchondral bone contusion ("bone bruise") adjacent to a cartilage lesion helps in the diagnosis of acute chondral lesions. Traumatic bone marrow alterations regress in most cases over the course of 6 months. For this reason the initial MRI should be performed within 1 to 6 weeks after trauma. A follow-up study should be undertaken not prior to 3 months after injury. Osteoarthritic cartilage lesions show a distinct regional pattern on MRI usually affecting the weight-bearing regions. In advanced stages, regularly concomitant osseous reactions such as osteophytes, subchondral sclerosis and bone attrition are observed. Subchondral bone marrow lesions in osteoarthritis show a tendency to progress., Conclusion: The direct inspection and probing of the joint during arthroscopy allows for a detailed assessment of the chondral surface and the diagnosis of possible cartilage softening. An arthroscopic differentiation between acute traumatic chondral lesions and chronic cartilage alterations is possible in most cases within the first 6 to 12 weeks after injury.

With the advent of magnetic resonance imaging (MRI) after knee injuries interest has focussed on the clinical relevance of different concomitant osseous damage. Different MRI- sequences reveal varying characteristics of such lesions. Prospective data of 69 patients with MRI-detected sub-acute subchondral fractures or bone bruises according to the classification of Mink was recorded. Function, symptoms (Noyes) and activity (Tegner) were assessed at the time of first MRI and 7,4 months later including a follow-up MRI using T 2-weighted fat saturated (fs) fast-spin-echo-sequences (FSE), T 1-weighted spin echo (SE) sequences, Proton-density-weighted spin echo-sequences (SE) and T 2-weighted (fs) gradient-echo-sequences. The patients were divided in 4 groups: patients with subchondral fracture and patients with pure bone bruise subdivided in patients with and without intraarticular knee lesions. Bone bruises were diagnosed in 44 cases, subchondral fractures in 25 patients. Patients without intra-articular pathology had significantly poorer function at the time of MRI with subchondral fractures, but not in the sub-group with intra-articular damage. Symptoms were not significantly different in both groups at this time. At 7,4 months both sub-groups with fractures had a lower level of function compared to patients with bone bruises, activity score and symptoms showed poorer results in the group without intraarticular lesion (p = 0,01 for all scores). T 1- weighted spin echo (SE) sequences revealed to be the most important tool to differentiate the various lesions. Hints for a modification of rehabilitation avoiding axial forces in case of subchondral fractures might be the use of isokinetics using open kinetic chain instead of closed kinetic chain or orthosis with relief of the affected compartment.

Arthrofibrosis is a disabling complication after knee trauma and surgery and is characterised clinically by joint stiffness. Due to an immune response, the proliferation of fibroblasts and synthesis of extracellular matrix proteins are increased. The cytokines transforming growth factor beta (TGF-beta) and platelet-derived growth factor (PDGF) are critical players in tissue fibrosis, stimulating cell proliferation and the production of various extracellular matrix proteins. Tissue samples from the infrapatellar fat pad and intercondylar synovia of seven patients (age 18-49 years) suffering from arthrofibrosis were taken at surgery. The mean interval between trauma and arthrolysis was 14.3 months. All samples were stained with haematoxylin and eosin, and monoclonal and polyclonal antibodies were applied for immunohistological localisation of TGF-beta and PDGF. The percentage of both cytokines was then analysed using an image analysis system. Tissue samples with no macroscopic pathology of the synovial tissue from eight patients for anterior cruciate ligament replacement served as controls. Immunostaining for TGF-beta and PDGF was found to be increased in arthrofibrotic tissue. Both cytokines could be detected subsynovially around inflammatory cells. The profibrotic cytokines TGF-beta and PDGF play an important role in the pathogenesis of arthrofibrosis. Both cytokines are key mediators of tissue fibrosis.

Like no other joint of the human body the knee depends on intact ligaments. Knee instability due to ligament injuries will cause abnormal joint kinematics, and thereby is made responsible for secondary damage to other important knee joint structures. Diagnosis of knee ligament injuries is based on the detailed history with often typical injury patterns, as well as on the physical examination with specific knee ligament tests. In addition radiological evaluation is used. The range of knee ligament injuries is wide. Beginning with an isolated medial collateral ligament rupture which will heal with conservative treatment, they range to knee dislocation, a serious injury which needs emediate care and is associated with a high incidence of complications. Surgical procedures aim to reconstruct knee ligaments as anatomical as possible to provide for a long term stable knee joint.

Lesions of the TFCC are currently a diagnostic and therapeutic challenge. Disc-injuries are often not identified and, therefore, acute ruptures are unfortunately not always immediately repaired. Moreover, therapeutic measures are still sparse and informative trial results are lacking. An anatomical, pathological, diagnostic and therapeutic comparison with the meniscus of the knee is possible.

Aim: The purpose of this study was to evaluate different clinical meniscus tests., Method: During 13 months we evaluated 64 patients with a suspected meniscus lesion in a prospective study. The age ranged from 16 to 76 years (average: 38.5 years). 66 % were male patients. Between the clinical examination and the arthroscopy there was no additional trauma to the knee. All patients were clinically examined in a standard manner by two independent orthopaedic surgeons. Clinical findings of the menisci were documented according to 12 well-described and commonly used meniscus tests. The arthroscopy was performed by a single surgeon who was not aware of the results of the clinical examination. This surgeon documented the intraarticular findings in a standardized operating report. A meniscus lesion/degeneration was documented when this was evident either by inspection or by palpation., Results: The results showed either clinical meniscus tests with a high specificity and a low sensitivity or tests with a high sensitivity, but only a low specificity. We were not able to identify meniscus tests which showed both a high sensitivity and a high specificity., Clinical Relevance: Even with access to MRI the clinical findings in knee joint with injured menisci still have a high diagnostic value. However, it seems to be necessary to combine different tests.

Aim: The operative treatment of posterior knee instability is a difficult problem and the literature does not offer methods as good as ACL reconstruction., Methods: With a new operative approach the authors have attempted to improve the surgical procedure and the final outcome in terms of stability and function. To illustrate our clinical findings, 20 cases of chronic posterior-lateral knee instability were retrospectively reviewed following PCL reconstruction. We examined 5 women and 15 men. The average follow-up period was 14 months (6 - 24 months) and the average age was 30 (17 - 59) years., Results: Subjectively all patients were satisfied with the surgical outcome and there were no intraoperative technical difficulties and no patient had a postoperative problem. The p.-a. instability measured at 20 degrees of knee flexion was preoperatively 11.7 mm, postoperatively 7.2 mm and 6.7 mm on the uninjured side. The Lysholm score was preoperatively 59 (35 - 71) points and postoperatively 85 (65 - 100) points. 19 patients returned to work and 14 patients were able to participate in sports., Conclusion: The results demonstrate that the knee still does not have a normal stability postoperatively, but the results were reproducible and the method appears to be reliable.

Aim: The aim of this work was to control the results after simultaneous use of different modern resurfacing techniques., Methods: We examined the patients who were subjected to different cartilage repair methods using the ICRS score (anterograde drilling, autologous chondrocytes transplantation, OATS, refixation with resorbable pins, spongious bone grafting, HTO)., Results: In two cases the combination of different cartilage regenerative methods in a one-step technique produced a good reconstruction of the joint surface with good clinical outcome. With the implantation of carbon plaques, osteolysis of the spongious bone in combination with an incomplete defect filling can be observed. The therapy must be individual and take the clinical, radiological and intraoperative findings into consideration., Conclusion: The combination of different resurfacing techniques may have success only if the biomechanical properties of the joint with axial malpositioning and ligament instabilities are considered and treated as well. New prospects are offered particularly for young patients with extensive cartilage damage and without other therapeutic options.

A review of the literature revealed that there are no new scientific data which can rule out the existence of an isolated traumatic meniscus tear. However, the large number of publications on the subject of meniscus pathology do suggest that the traumatic tear of a "healthy" meniscus without ligamental or osseous concomitant lesions is indeed very rare. In order to perform an individual medical examination, therefore, medical experts need every available information to assess such a case.

Reconstruction of the ruptured anterior cruciate ligament (ACL) using modern techniques achieves successful long-term results in up to 90% of all cases. Yet the discussion continues as to the suitable implant to replace the ACL in terms of donor morbidity, implant reaction, long-term results, and potenzial risk of carrier concerning the allograft. The clinical and histological results from 2 years experience with the BPTB allograft (Tutoplast) and the BPTB autograft for ACL reconstruction are compared with reference to stability, functionality, rerupture rate, and histological reaction of the remodelling process. A BTB patella tendon allograft was implanted into 132 patients and a BPTB autograft into 136 patients. The patients were randomly allocated to the two groups. The results were recorded by an independent researcher and assessed according to the IKDC and Lysholm score. In the allograft group, a total of 20 patients (2.6%) reruptured within an average period of 11.75 months. In the autograft group, the transplant reruptured in five patients (4.8%) after an average of 17 months. Histological reappraisal indicated delayed incorporation and extended reconstruction in the BPTB allograft. There were clearer and more protracted indications of hypercellularity and hypervascularity, and the collagen matrix had not regularly aligned longitudinally even 1 year later. A detailed analysis of the BPTB allograft group indicated that especially in young and very sporty patients there is increased elongation of the implant and a clearly higher rerupture rate. Hence, according to the data we have collected, it would seem that the use of the BPTB allograft (Tutoplast) is not suitable especially in young patients who frequently practice high-level sports involving high knee stress.

The knee, the largest joint in the human body, is composed of the distal femur, the proximal tibia, the patella, and a complex arrangement of ligaments and menisci. This joint is particularly vulnerable because of its anatomic, functional, and mechanical characteristics. Depending on the severity and the specific mechanism of the trauma, injuries of soft tissue structures or bony elements or even a combination of both may be present. In case of severe pain caused by traumatic events clinical tests may be insufficient for exact diagnosis and radiological examinations are mandatory for an effective planing of the therapeutic management.

Stress fractures occur in 13.2-37.0% in running athletes. There is a decreasing incidence of these fractures in the tibia (33%), navicular (20%), metatarsus (20%), femur (11%), fibula (7%) and pelvis (7%). Clinically stress fractures present themselves with uncharacteristic local pain under weightbearing conditions. In 75% the medial tibial crest is involved. Usually the pain disappears when the patient is non-weightbearing. As causal factors wrong training methods, oligomenorrhoe (6x incidence), low nutrition input (8x incidence) and a genu recurvatum-morphotype can be found. Misinterpretation can result from a similar clinical and radiological (conventional x-ray, scintigraphy, MRI) early course in stress fractures and bone tumors. We present a patient with a clinical diagnosis of a meniscus lesion. The following MRI was suspect for a malignant lymphoma or histiocytoma. Biopsy was performed and showed the final diagnosis of a stress fracture.

Introduction: The treatment of full-thickness cartilage defects still represents a problem that has not yet been solved satisfactorily. Current methods used to cover defects in the knee joint are osteochondral cylinder transplantation (OCT) and autologous chondrocyte transplantation (ACT)., Methods: With a prospective clinical investigation, at the time being with 2-year results, we have examined ACT in comparison to OCT in 20 patients with regard to clinical and histomorphological (histology, immunohistochemistry, RES) outcome., Results: We found equally good results with both methods in Lysholm, Meyers and Tegner Activity Scores. Histomorphologic evaluation of biopsies obtained by arthroscopy after ACT showed a defect filling in all cases, mainly with fibrous cartilage, while localized areas of hyalinelike regenerative cartilage were documented near the base. We did not see any histomorphologically visible change in the transplants after OCT., Conclusion: At the time we prefer OCT instead of ACT given the correct indication.

Although long-term results in cruciate ligament surgery are continuously improving, we are still confronted with a certain rate of surgical failures and an increasing number of revision procedures. Despite a tremendous effort towards experimental and clinical research in the field of anterior and posterior cruciate ligament surgery over the past decades, there is still a strong need to further improve results. Therefore, the goal of the present paper is to introduce and discuss new developments in the rapidly changing field of cruciate ligament surgery, in order to give the clinician a base for discussion to include these developments in their daily clinical work. The present paper focuses on current developments and future perspectives such as biodegradable implants, new aspects in graft selection, double-bundle posterior cruciate ligament reconstruction, possibilities of biological intervention with growth factors, and the new technology of robotics and navigation.

Arthrofibrosis is a disabling complication after trauma and surgery due to massive connective tissue proliferation. The etiology and pathogenesis have never been fully understood. A strong immune response may lead to activation and proliferation of fibroblasts with excessive and disordered deposition of matrix proteins. In similar pathological conditions, like lung fibrosis or superficial fibromatoses with fibrotic transformation an increased expression of collagen type VI has been reported. We investigated fibrotic tissue samples taken from 18 patients (average age: 32.7 years), who underwent arthrolysis of the knee joint because of symptomatic arthrofibrosis following ligament injury. The mean interval between trauma and arthrolysis was 13.8 months (range 4-50 months). Tissue samples were taken from the infrapatellar fat pad and intercondylar connective tissue. All samples were stained with HE. The expression of type III and VI collagen was studied immunohistochemically using an immunoperoxidase method for light microscopic visualization. Histologic analysis from patients with arthrofibrosis showed a synovial hyperplasia with cell infiltration and vascular proliferation compared to synovial tissue samples from knee joints without any detectable pathology. Subsynovial an increased deposition of matrix proteins was visible. Type VI collagen was widely distributed as a network subsynovial and around capillary walls. Type III collagen showed a diffuse distribution. Arthrofibrotic tissue is, similar to pathological conditions with fibrotic transformation characterized by an increased expression of collagen type VI. Collagen type VI may play an important role in matrix homeostasis. It serves as an anchoring element between collagen fibers and as a cell binding structure.

Cartilage defects in the knee joint are common and have a bad tendency for healing due to the limited regeneration of hyaline cartilage. Surgeons have an ample choice of various operative treatment measures. Especially for the treatment of larger lesions first results of autologous chondrocyte transplantation (ACT) were published in 1994 [3]. Autologous chondrocytes are isolated from an arthoscopically harvested cartilage biopsy, cultured in vitro and implanted in the defect under a periostal flap in a second procedure. In an international multicenter study 1,051 patients treated with ACT between 6/95 and 12/98 were documented with follow-up examinations after 12 months (588 patients), 24 months (220 patients) and 36 months (40 patients). The majority of the defects (61.2%) were localized on the medial femoral condyle, measuring 4.6 cm2 and mostly described as grade III/IV lesions. The clinical evaluation was performed using a modified Cincinnati knee rating system independently for clinician and patient. Evaluations showed an increase from 3.35 to 6.25 after 24 months and from 3.10 to 6.77 in a scale from 1 (bad) to 10 (excellent). ACT favours defects of the femur with an improvement rate of 85%. Adverse events possibly related to ACT were described in 4.8% of the patients. Diagnostic second-look arthroscopies are included in the reoperation rate of 5.1%. The presented data indicate autologous chondrocyte transplantation as an effective and safe option for the treatment of large full thickness cartilage defects in the knee joint.

We review our results with an animal model for investigations on the development of osteoarthritis (OA). This model is based on running exercises of wistar rats performed in a running wheel using intracranial self-stimulation to motivate rats to excessive running. In our studies a total of 49 rats was divided into groups with running exercises of 15 km, 20 km, and 30 km respectively. In order to investigate the influence of altered sensible joint innervation on the development of OA, in addition to a total running load of 20 km in another group of 8 rats we performed Capsaicin (8 Methyl-N-vanillyl-6-noneamide) mediated partial sensible knee joint denervation. Complete knee joint sections of all rats were evaluated histologically using Mankins grading system. In addition, we performed semiquantitative assessment of the immunoreactivity of the chondrocytes to MMP-3 by immunostaining with monoclonal MMP-3 IgG antibodies. Histological assessment and immunostaining for MMP-3 of the knee joint sections revealed a significant increase in osteoarthritic changes with higher running load. Moreover, osteoarthritic changes in the knee joints of the rats with sensible joint denervation and running exercises were significantly greater as compared to those with sole running load. In conclusion, our studies revealed a significant relationship between the development of knee osteoarthritis and the extent of joint load. Hereby, an alteration of the sensible joint innervation seems to have a promoting effect on the development of osteoarthritic changes. This model offers a wide range of further approaches to studying different processes of the development of OA.

Cartilage defects still represent an unsolved problem in joint surgery. The intrinsic healing capacity of cartilage is insufficient and at best leads to reparative tissue like fibrous cartilage or cartilage like tissue regardless of the therapy applied. Cell culture techniques and generation of tissue specific matrix tread new paths to treat traumatic cartilage lesions. This technology referred to as tissue engineering allows for formation of constructs consisting of chondrocytes capable of production of cartilage specific matrix in combination with three-dimensional cell carriers. Polymers such as polylactid, co-polymers like polydioxanon with polyglactin and lyophilized dura have been used successfully to create such constructs with chondrocytes of different animal species. Cartilage specific compounds can be detected by histological and immunohistochemical techniques. To apply these constructs in humans, the distinguishing characteristics and problems of cell culture with human chondrocytes have to be considered. A further improvement of the artificially created tissue is conceivable using growth factors even including genetic manipulation of the applied cells.

A 58-year old man with Wilson's disease sustained a bilateral spontaneous rupture of the quadriceps tendon. The histological investigation showed advanced degeneration of tendon structure and copper deposits. After tenosuture the patient had complete cure with full range of movement. We discuss about relation of Wilson's disease, copper deposits and degenerative changes of tendon tissue.

The use of degradable implants in recent years has brought not only good results. Foreign body reactions to implantation of degradable polymers clearly curtailed the initial expectations. Bioabsorbable polymers have been used for sutures, vascular clips, and fixation implants for both intra-articular fractures and malleolar fractures. In the literature these implants are controversial. Potential benefits remain for the use of this material for interference screws if the problems of inflammation are minimal and the fixation properties are sufficient. There is no need for a second operation for removal. In one patient, 4,5 years after to implantation of an degradable interference screw (Copolymer 85/15 D,L lactide glycolide; Biologically Quiet, Instrument Makar, Inc. Mount Hope, MI 48864, USA) we took an biopsy and made histological examinations. No foreign body reaction or inflammation signs could be detected.

A chronic inflammatory reaction and an increased expression of Ki-67 positive cells in arthrofibrotic tissue and the increased proliferation of fibroblasts from arthrofibrotic tissue could be due to an immunopathological reaction. Compared to systemic and organ fibrotic tissue arthrofibrotic tissue is characterized by an increased expression of collagen type VI.

Treatment with autologous chondrocyte transplantation (ACT) leads to regeneration of hyaline cartilage. Since September 1996, 52 patients have been treated. Eleven patients were screened clinically and by MRI 18 months later. The biopsy specimen from the transplanted area showed formation of hyaline cartilage.

Question: The accuracy of ultrasound in the detection of histological changes is a point of discussion., Method: In an experimental study we examined on 58 explanted human patellar tendons the correlation between histological and sonographic changes., Results: Ultrasonographic measurements of length, width, thickness and circumference of the ligaments correlated highly to the explants' macroscopic evaluated dimensions. The sonographic lesions were distinguished in changes in form and echogenicity. Macroscopic visible changes in the explanted ligaments could be detected ultrasonographically. In histological aspect 2 tendons and in ultrasonographical aspect 16 tendons were found to be normal in the whole course of the tendons. 14 ligaments showed histological but not ultrasonographical abnormalities. 42 ligaments were conspicuous in both methods of examination. In the course of the tendons a very high correlation (up to 92%) between sonographical and histological findings was detected. At the insertion are of the patellar ligament the correlation was low., Conclusion: The performed study shows that ultrasonographically detected lesions of the patellar ligament point to histological changes but no conclusions to the kind of histological changes can be taken. However ultrasonographically found abnormalities correlate in a high proportion to histologically detectable changes in the ligaments. Ultrasonography is a good method to evaluate degenerative symptoms in the patellar ligament.

The results of magnetic resonance imaging (MRI) were compared with those of arthroscopy in a prospective series of 276 patients. A "dedicated system" for MRI of limbs and peripheral joints--the 0,2 Tesla ARTOSCAN (ESAOTE, Italy)--was used for imaging knee joint lesions. T1-weighted spin echo sagittal images, T2-weighted gradient-echo coronal images, and axial views for lesions of bone and the femoropatellar joint were acquired. If necessary paraxial sagittal and oblique coronal views were obtained for imaging of the cruciate ligaments. This protocol allowed excellent visualization of the cruciate ligaments, medial and lateral meniscus in almost all patients. Compared with arthroscopy performed within 48 hours after imaging, the sensitivity, specificity, and accuracy were respectively, 91, 92 and 91 per cent for tears of the medial meniscus; 80, 96, and 92 per cent for tears of the posterior meniscus; 100, 100, and 100 per cent for tears of the posterior cruciate ligament; 93, 98, and 99 per cent for tears of the anterior cruciate ligament; and 73, 100, and 92 per cent for full-thickness articular cartilage lesions. The examination can be performed within 30 to 45 minutes at a cost that is lower than that of diagnostic arthroscopy. ARTOSCAN imaging is a safe and valuable adjunct to the clinical examination of the knee and an aid to efficient preoperative planning.

At present no established therapy for the complete loss of meniscus is available. An attempt is made to create a transplant out of autogeneic tissue resembling the meniscus in its morphological and functional aspects. The middle third of the patellar tendon with proximal and distal bone blocks serves as a basis and is coated with a fascia lata strip. After temporary subcutaneous transfer, the meniscus substitute is intended for later transplantation. The theoretical ideas for the imitation of a meniscus in view of fibre architecture and biomechanical validity were tested in 14 sheep. In principal this model succeeds in imitating the fibre architecture of the menisci. After a conditioning period of 8-10 weeks in the subcutaneous tissue, the neomeniscus seems to be suitable for transplantation. The tensile strength of the grafts decreases slightly but the bone blocks stay viable.

The human posterior cruciate ligament (7 unselected specimens) consists of 2 different bundles with a common tibial attachment: 1. a thin, flat and slightly twisted posterior bundle running to the posterior medial condyle taut in extension and lax in flexion of the knee, 2. a thick oval anterior bundle with parallel fibers running to the roof of the notch lax in extension and taut in flexion. This contra-tensile function explains the different posterior instability in extension or flexion of the knee in case of an isolated rupture of only 1 of these bundles.

The treatment of injuries to the posterior cruciate ligament (PCL) remains controversial. Various problems have prevented PCL reconstruction from consistently producing the knee stability desired. Biological graft tissue undergoes a remarkable healing process comprising different phases. The strength of autogenous graft material decreases soon after the operation. During this early healing phase synthetic augmentation could protect the graft tissue from overloading or overstretching, supporting the tissue restoration process. In order to evaluate the morphological effects of the ligament augmentation device (LAD) on a free patellar tendon autograft in PCL reconstruction a comparative study in sheep was conducted. In 24 mature sheep the PCL was replaced with either a patellar tendon autograft alone or a patellar tendon autograft augmented by the LAD. The LAD was fixed at both ends. The animals were not immobilized after the operation. Tibial fixation was released 8 weeks after the operation. The autografts of both groups were histologically evaluated after 2, 6, 16, 26, 52 and 104 weeks. In addition to necrotic and degenerative alterations a pronounced inflammatory reaction could be seen in the LAD-augmented autografts soon after the operation. Compared with the non-augmented autograft, tissue formation and remodeling was delayed in the augmented group. After 1 and 2 years, the morphology of the autograft tissue was similar in the augmented and the non-augmented group and was different from that of a normal PCL. The LAD was surrounded by a chronic inflammatory reaction, and collagen fiber ingrowth into the LAD was not observed. Transmission electron microscopy showed that small-diameter collagen fibrils were predominant in the graft tissue of both groups. Thus, better remodeling of the autograft tissue in the presence of the LAD was not demonstrable in this particular study. The value of synthetic augmentation of biological grafts of PCL reconstruction seems to be questionable at present.

Experimental data and clinical experience with ultrasonography have demonstrated good results in the evaluation of internal derangements of the knee. But the value of ultrasound of the menisci still is controversial. The following investigations compare sonography with histologic results. In a water bath 64 cadaveric menisci were examined with a 5 MHz phased array sector scan. Pathologic conditions like natural or artificial tears, meniscal degeneration and crystal deposition diseases gave different echoes. In cases of vertical meniscal tears, a sharp and bright line-echo is seen on the screen. Due to this consistent reflexion, different types of meniscal tears cannot be differentiated by ultrasound. Severe degrees of meniscal soft tissue degeneration, proven histologically, were shown as hypoechoic areas. Following this experimental results, sonography is a useful modality in the diagnosis of meniscal disorders.

Introduction: Stäubli postulated a clinical significance of lesions to the popliteus system because of a 95% incidence in acute and 85.7% in chronic ruptures of the cruciate ligaments. The sparse clinical literature on this topic favours conservative or operative treatment as well., Objective of the Study: What is the significance of isolated lesions of the popliteus tendon on translational stability of the knee joint?, Material and Methods: The popliteus tendon was severed in six sheep. One year postop. the knee joints were evaluated by means of x-ray, biomechanical testing, computed tomography osteoabsorptiometry (CTOAM) and micromorphology., Results: There were no pathological findings on x-ray. The simulation of the trauma situation ex vivo showed no instability whereas increased translation and progressive loosening of secondary stabilizers was found after one year (posterior and total aptranslation, compliance index p < 0.05). The position of the density maxima of the subchondral mineralization are about the same on the operated and the non-operated knee joint. All tendons healed macroscopically, but micromorphology exhibited a persisting increase of cross-sectional areas, a low differentiated ultrastructure of the tendon and an increased cellularity (p < 0.01)., Experimental: 1. intraarticular, extrasynovial tendons heal spontaneously even within the synovial environment; 2. healing is defective even one year postop.; 3. the postulate of the significance of the popliteus system for the stability of the knee is proven. Clinical: 1. (isolated) lesions of the popliteus go undetected with clinical and instrumented examination; 2. conservative treatment eventually results in increased posterior translational instability; 3. this will increase strain and load on the menisci and ACL- reconstructions.

The bone-patellar tendon-bone graft is currently the best substitute for the anterior cruciate ligament (ACL). To improve the results we compared a modified Jones procedure with an additional PDS augmentation. In 25 sheep the ACL was reconstructed in the left knee after total resection. The only resection of the ACL was done in all right knees. One year postoperative 21 sheep remained in the experiment and came to evaluation. There were 10 modified Jones procedures and 11 PDS augmentations. In both groups, the central one-third of the patellar tendon was implanted through a femoral and tibial drill hole for reconstruction of the anterior cruciate ligament. The transplants were fixed on both ends with a 1-mm cord of polydioxanon (PDS), a soft preload of 50 N was given with a spring balance and the ends of the cords were fixed with a screw and a washer. In the second group we did an additional augmentation with a doubled cord of 2 mm PDS. Early mobilization and weight-bearing was allowed. Throughout the observation period all animals were labelled for fluorescence microscopy. One year after resection of the ACL without reconstruction there were totally destroyed joints. Histology showed damaged menisci and joint surfaces without any cartilage as a sign of severe arthrosis. The macroscopic aspect of the transplants showed strong ligaments coated totally by a synovial membrane with good vascularization. Only little signs of degeneration were to be seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Histological examination of 1660 biopsies (2-5 mm) of the synovial membrane of 317 patients were obtained by arthroscopic dissection; in 70% of all cases non-specific changes were revealed and in 30% specific changes. The findings included different stages of proliferation of the superficial layer, uncharacteristic inflammatory reactions of the stratum synoviale and fibrosis of the stroma, vascular proliferation and pseudopolypoid thickening of the synovial membrane. The histomorphological findings can only be interpreted reliably and a pathogenetic classification obtained, e.g., detritus synovialitis, rheumatoid arthritis or post-traumatic changes, if the arthroscopic findings conclude an exact documentation of the biopsy site and the clinical findings.

The patellar tendon autograft is widely used in cruciate ligament replacement. Knowledge of the basic processes involved in graft healing and of factors regulating the healing process is still limited. The patellar tendon and cruciate ligament are morphologically and biochemically distinct, which reflects the different mechanical forces acting on them. Based on morphological studies in posterior cruciate ligament replacement in a sheep model, the patellar tendon autograft undergoes a remarkable transformation process during healing. Distinct healing phases similar to those in would healing can be differentiated. During the phase of necrosis and degeneration the graft tissue becomes disorganized and mechanically weak. During the following phase of revitalization, which is characterized by revascularization, cellular proliferation and formation of collagen and other components of the extracellular matrix, the mechanical properties gradually improve. Even after the phase of remodeling the autograft tissue differs structurally and mechanically from a ligament, suggesting that the autograft only heals to a scar-like replacement tissue. The lack of a fascicular structure, the widespread presence of type III collagen and fibronectin, and the predominance of thin collagen fibrils correlate with a maximum stress of 60% and an elastic modulus of 70% compared with control values. In the sheep model cartilage alterations in the treated knees are similar to those in controls even though reconstruction of the posterior cruciate ligament cannot restore joint stability of controls.(ABSTRACT TRUNCATED AT 250 WORDS)

The position of transcondylar small caliber drill tunnels after reattaching of femoral avulsions of the anterior cruciate ligament usually escapes objective verification by conventional roentgenography. A model of investigation and the results of cadaver studies are presented: Stored CT data are used for 3D-reconstruction of the distal end of the femur. In such manner the sites of perforation of the K wires can be determined unequivocally and distinctly.

Not every reconstruction of the anterior cruciate ligament is successful. Possible reasons for failure are renewed severe trauma, inadequate fixation of the transplant, an isometric mistake, weak transplant material, an anterior cruciate ligament reconstruction performed in isolation in a complex unstable knee, or prosthetic ligaments. Revision surgery is indicated when patients complain about the recurrence of knee instability. Preoperative diagnostic procedures must include X-rays with the knee in defined positions in order to determine drill hole courses and visualize any signs of arthrosis and the patellar position. Revision surgery is hampered by disadvantageously placed drill holes, exhaustion of the supply of transplant material, secondary instabilities, gonarthrosis or a possible arthrofibrosis. During rehabilitation a variable knee position is imperative, because of the different procedures that might need to be implemented.

Artificial ligaments have been used as augmentation devices, scaffolds, ingrowth ligaments and even prostheses. The augmentation devices rely entirely on the autologous tissue for their function, whereas each of the other types functions more or less as a prosthesis. These devices can function only for a limited time and they are very sensitive to the implantation technique. Problems involve debris formation, synovitis and finally ligament rupture. There is also a loss of stability in the treated knee over the first 2-3 postoperative years. The clinical results obtained in various studies with the prosthetic devices are not satisfactory. The problem of reconstruction of a knee with ligamentous instability is far greater than that involved in replacing the ligament only.

In a prospective clinical study on 32 patients with Trevira ligament implants arthroscopic and histological findings were used to assess the articular effects of the synthetic ligament. In group 1 of patients with intact Trevira ligament no changes associated with foreign-body reactions were seen. In group 2 with abrased or frayed synthetic ligaments generalised foreign-body reactions in the suprapatellar recess as well as perivascular, round-cell infiltrates were seen in four out of six patients; four of the six cases also showed fibrotic signs indicative of prearthrotic changes. In group 3 with ruptured Trevira ligament no diffuse foreign-body reactions in the suprapatellar recess were seen in any of the 16 cases. In the intercondylar space foreign-body reactions correlating with the age of the implant were identified (p < 0.03). In 18% of cases with ruptured Trevira ligament generalised foreign-body reactions were seen; however, these changes were not accompanied by chronic inflammatory changes. Cases with technical shortcomings associated with a gradual fraying of the synthetic ligament invariably showed diffuse foreign-body reactions as well as chronic inflammatory infiltrates. In patients with spontaneous ligament rupture due to repeated trauma foreign-body reactions were restricted to the intercondylar space. In spite of the histological evidence of foreign-body granuloma no permanent clinical articular effects could be seen in our patients population within the follow-up time of up to 60 months.