Varying development of femoral and tibial subchondral bone tissue and their interaction with articular cartilage during progressing osteoarthritis.

INTRODUCTION: Differences between tibial and femoral joint surfaces and knee compartments concerning coupled bone and cartilage turnover or bone-cartilage cross talk have not been previously examined, although the mechanical and biological interaction of the mineralized subchondral tissues with articular cartilage is of great importance for advancing osteoarthritis. MATERIALS AND METHODS: Therefore, with the help of immunohistochemistry and real-time polymerase chain reaction (RT-PCR), human knee joint cartilage tissue was investigated for expression of key molecules of the extracellular matrix and cartilage composition (collagen type I and II, aggrecan) plus proteoglycan content (colorimetric analysis). Furthermore, we correlated the results with 3D microcomputed tomography of the underlying subchondral bone (high-resolution micro-CT system). Measurements were performed in dependence of the anatomical site (femoral vs. tibial, medial and lateral each) to identify regional differences during the osteoarthritic process. From an enduring series of 108 patients undergoing implantation of TKA, 34 osteochondral samples with lesions macroscopically classified as ICRS grade 1b (group A) and 34 samples with ICRS grade 3a/3b lesions (group B) were compared with 21 healthy controls. RESULTS: Concerning 3D analysis, the medial femoral condyle and tibia showed the most significant increase in bone volume fraction and a decrease in the trabecular number in group B frequently accompanied by subchondral bone resorption pits and enchondral ossification. Under physiological conditions, tibia plateaus show lower bone volume fraction than the corresponding femoral site and this difference enlarges with advancing OA. Partially even contradictory behavior was observed such as trabecular separation at the lateral tibial and medial plateau in osteochondral OA samples of the same patients. Collagen type II expression levels show faster and varying changes than type I during the OA process, leading to a lower positive or negative correlation with bone microstructural analysis, especially on the tibia plateau. CONCLUSIONS: Structural bone and cartilage parameter changes showed varying developments and correlations among each other in the different compartments of the knee. As a clinical conclusion, therapies to postpone or prevent cartilage degeneration by influencing the loss of mineralized bone could be site dependent.

Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: A guideline by the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU).

BACKGROUND: Autologous chondrocyte implantation (ACI) is an established and well-accepted procedure for the treatment of localised full-thickness cartilage defects of the knee. METHODS: The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Trauma (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning therapeutic consequences of primary cartilage lesions and the suitable indication for ACI. RESULTS: Based on best available scientific evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than three to four square centimetres; in the case of young and active sports patients at 2.5cm(2), while advanced degenerative joint disease needs to be considered as the most important contraindication. CONCLUSION: The present review gives a concise overview on important scientific background and the results of clinical studies and discusses the advantages and disadvantages of ACI. LEVEL OF EVIDENCE: Non-systematic Review.

[Autologous chondrocyte implantation (ACI) for cartilage defects of the knee: a guideline by the working group "Tissue Regeneration" of the German Society of Orthopaedic Surgery and Traumatology (DGOU)]. / Stellenwert der autologen Chondrozytentransplantation (ACT) in der Behandlung von Knorpelschäden des Kniegelenks - Empfehlungen der AG Klinische Geweberegeneration der DGOU.

Autologous chondrocyte transplantation/implantation (ACT/ACI) is an established and recognised procedure for the treatment of localised full-thickness cartilage defects of the knee. The present review of the working group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU) describes the biology and function of healthy articular cartilage, the present state of knowledge concerning potential consequences of primary cartilage lesions and the suitable indication for ACI. Based on current evidence, an indication for ACI is given for symptomatic cartilage defects starting from defect sizes of more than 3-4 cm2; in the case of young and active sports patients at 2.5 cm2. Advanced degenerative joint disease is the single most important contraindication. The review gives a concise overview on important scientific background, the results of clinical studies and discusses advantages and disadvantages of ACI.

Microencapsulation and chondrogenic differentiation of human mesenchymal progenitor cells from subchondral bone marrow in Ca-alginate for cell injection.

The application of stem cells is a promising therapeutic approach for cartilage regeneration. For cell therapies, a biocompatible injectable carrier, which improves retention and cell distribution and enables cell differentiation, is a prerequisite. In this study, Ca-alginate microcapsules containing human subchondral cortico-spongious progenitor cells were prepared and the chondrogenic differentiation potential was verified by real-time reverse transcription-polymerase chain reaction analysis of typical chondrogenic marker genes. The results confirmed that these cells were able to differentiate along the chondrogenic lineage when encapsulated in Ca-alginate microcapsules with a mean diameter of 600-700microm and stimulated with TGF-beta3. Chondrogenic marker genes type II collagen, aggrecan and cartilage oligomeric matrix protein were induced together with type I collagen, whereas adipogenic and osteogenic marker genes showed no induction over 14 days. After 28 days, proteoglycans and type II collagen were evident histochemically and immunohistochemically. Mechanical stability as well as permeability of Ca-alginate capsules were analysed over the course of cultivation and found to be qualified for stable cell immobilization and sufficient exchange of solutes. Therefore, from the cell biology point of view, Ca-alginate, an established hydrogel scaffold material is suited for regenerative therapies of cartilage defects based on the injection of progenitor cells.

Classification of graft hypertrophy after autologous chondrocyte implantation of full-thickness chondral defects in the knee.

OBJECTIVE: Graft hypertrophy is a major complication seen in autologous chondrocyte implantation (ACI) with a periosteal flap. We present the first magnetic resonance imaging (MRI) classification for periosteal hypertrophy including a grading of clinical symptoms and the surgical consequences. METHODS: One hundred and two patients with isolated chondral defects underwent an ACI covered with periosteum and were evaluated preoperatively, 6, 18 and 36 months after surgery. Exclusion criteria were meniscal pathologies, axial malpositioning and ligament instabilities. Baseline clinical scores were compared with follow-up data by paired Wilcoxon-tests for the modified Cincinnati knee, the ICRS (International Cartilage Repair Society) and a new MRI score including the parameters defect filling, subchondral edema, effusion, cartilage signal and graft hypertrophy. Hypertrophic changes were graded from 1 (minimal) to 4 (severe). RESULTS: All scores showed significant improvement (P<0.001) over the entire study period. Patients with femoral lesions had significantly better results than patients with patella lesions after 18 and 36 months postoperative (P<0.03). Periosteal hypertrophy occurred in 28% of all patients. Fifty percent of all patella implants developed hypertrophic changes. No patient with grade 1, and all patients with grade 4 hypertrophy had to undergo revision surgery. The Pearson correlation between graft hypertrophy and ICRS score was 0.78 after 6 months, and 0.69 after 36 months (P<0.01). Inclusion of graft hypertrophy in the MRI score improves the correlation to clinical scores from 0.6 to 0.69. CONCLUSIONS: Grading graft hypertrophy helps to identify patients needing an early shaving of the graft. Its integration into an MRI score improves correlation with clinical scores. Re-operation depends on the grade of hypertrophy and clinical symptoms.

Results after microfracture of full-thickness chondral defects in different compartments in the knee.

OBJECTIVE: To determine if the clinical results after microfracture of full-thickness cartilage lesions deteriorate over a period of 36 months. METHODS: Between 1999 and 2002 85 patients (mean age 39.5 years) with full-thickness cartilage lesions underwent the microfracture procedure and were evaluated preoperatively and 6, 18 and 36 months after surgery. Exclusion criteria were meniscal pathologies, axial malpositioning and ligament instabilities. Baseline clinical scores were compared with follow-up data by paired Wilcoxon-tests for the modified Cincinnati knee and the International Cartilage Repair Society (ICRS)-score. The effects of the lesion localization and Magnetic resonance imaging (MRI) parameters were evaluated using the Pearson correlation and independent samples tests. RESULTS: Both scores revealed significant improvement 18 months after microfracture (P<0.0001). Within the second 18 months after surgery there was a significant deterioration in the ICRS-score (P<0.0001). The best results could be observed in chondral lesions of the femoral condyles. Defects in other areas of the knee deteriorated between 18 and 36 months after microfracture. MRI 36 months after surgery revealed best defect filling in lesions on the femoral condyles with significant difference in the other areas (P<0.02). The Pearson coefficient of correlation between defect filling and ICRS-score was 0.84 and significant at the 0.01 level. CONCLUSIONS: Microfracture is a minimal invasive method with good short-term results in the treatment of small cartilage defects. A deterioration of the results starts 18 months after surgery and is most evident in the ICRS-score. The best prognostic factors have young patients with defects on the femoral condyles.

Subchondral bone trauma causes cartilage matrix degeneration: an immunohistochemical analysis in a canine model.

UNLABELLED: Joint instability was believed to be the main cause of osteoarthritis following non-fracture articular trauma. However, sudden high impact load through articular cartilage onto subchondral bone may also cause osteoarthritic changes. OBJECTIVE: We asked whether early osteoarthritic changes following transarticular impact may be depicted using immunofluorescence on unfixed cryosections to contribute to a more detailed understanding of degenerative processes of joint impaction. DESIGN: Transarticular impacts were applied to patellofemoral joints of 12 skeletally mature beagle dogs (age: 15-16 months) using a drop tower. Biopsies of impact areas were sampled after 6 months and processed for standard light microscopy on formalin-fixed sections and for immunofluorescence for collagen type I (col I), type II (col II) and aggrecan (AC) on unfixed cryosections. Gross morphology and immunofluorescence on cryosections were documented using a semi-quantitative scaling system, compared to healthy controls and to standard light microscopy. RESULTS: Four biopsies showed almost entirely fibrocartilaginous morphology, four appeared to be of preserved hyaline morphology with only minor signs of fibrocartilaginous remodelling and four showed preserved hyaline appearance. We found decrease in col II and AC expression in highly degenerative specimens as well as increase of col I expression. Increased col I expression in the pericellular matrix could even be depicted in specimens with intact hyaline morphology. DISCUSSION/CONCLUSION: Observations suggest that joint impaction causes early osteoarthritic changes after 6 months. Collagen network disruption seems to lead to AC loss, although other researchers found isolated AC loss without denaturation of col II using immunofluorescence in formalin-fixed specimens. This is the first study on effects of transarticular impact using immunofluorescence on unfixed cryosections.

An experimental canine model for subchondral lesions of the knee joint.

Aim of the study was to create an animal model for the investigation of the role of subchondral bone damage without initial cartilage lesion in the pathogenesis of osteoarthritis, the mechanical properties of the joints as well as its role in cartilage metabolism. Therefore, after cadaver studies an animal model was created to apply a transarticular load to the femoro-patellar joint under reproducible conditions and produce a pure subchondral damage without affecting the articular cartilage. Following the cadaver studies a first group of four dogs was impacted to identify forces to produce isolated subchondral fractures in the femoral condyle. Then a second group of 12 dogs knee joints was impacted under identical conditions with forces of approximately 2100 N to produce similar subchondral fractures without cartilage damage in one joint under MRI control: T1-weighted SE-sequences. T2-weighted TSE, fat suppressed TIRM-sequences and 3D-FLASH fat saturated sequences. FLASH 3D-sequences revealed intact cartilage after impact in all cases and TIRM-sequences showed subchondral fractures representing bleeding, microfractures and fragmented bone trabecules. Turbo spin echo sequences and T1-weighted images revealed other intact intraarticular structures such as ligaments and menisci. The proposed experimental animal model is suitable to investigate the effect of pure subchondral damage on the articular cartilage and on means of treatment of cartilage defects without surgical intervention and without initial cartilage damage.

Experimental autologous osteochondral plug transfer in the treatment of focal chondral defects: magnetic resonance imaging signs of technical success in sheep.

PURPOSE: To describe the magnetic resonance imaging (MRI) signs of technically successful osteochondral plug transfer and to correlate the findings with histology using the Mankin score. MATERIAL AND METHODS: The study was done in a prospective animal experiment: 11 adult black-head sheep underwent surgical treatment with osteochondral plug transfer of a knee joint. The animals were killed 6 months later and MRI of the joints was done immediately. MRI was applied with a 1.5T MR scanner using a spin-echo (SE) T1-weighted, turbo spin-echo (TSE) T2-weighted with spectral fat suppression and a fat-suppressed 3D-spoiled gradient echo (GRE) sequence (manufacturer's acronym: FLASH) (TR 50.0 ms, TE 11.0 ms, flip 35 degrees). After MRI, all knee joints were dissected and a biopsy of the plug and the adjacent cartilage was taken. Classification of the cartilage biopsies was carried out in accordance with a modified Mankin score. RESULTS: Cartilage repairs with a hypointense cartilage signal in the FLASH 3D sequence were correlated with poor histological results (lower Mankin score). Histologically, the regions of cartilage with a hypointense signal showed a fibrocartilage-like repair tissue. Hyaline cartilage with well-defined layers had the same signal intensity in the FLASH sequence relative to adjacent hyaline cartilage. There were two plugs with a surface defect, graded as Outerbridge grade 1 in MRI and histology. Both had a poor outcome in the histologic Mankin score. Grade 2-4 lesions were not observed in the MRI study nor in the histologic study. CONCLUSION: MRI is a useful non-invasive tool for evaluating the morphologic status of osteochondral plug transfers. A good postoperative result of the cartilage repair was found histologically if an isointense cartilage signal of the graft was documented in the FLASH 3D sequence, and the graft had good congruity with the articular surface without defects.

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)]. / Indikations- und Durchführungsempfehlungen der Arbeitsgemeinschaft "Geweberegeneration und Gewebeersatz" zur Autologen Chondrozyten-Transplantation (ACT).

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

[Tissue engineering: chances and challenges for application in rheumatic diseases]. / Tissue EngineeringChancen und Herausforderungen für die Anwendung in der Rheumatologie.

Current technologies of tissue engineering offer new strategies for the treatment of cartilage and bone defects. Beyond implantation of cell suspensions, second generation products of biomaterial enforced with in vitro preformed tissues are clinically applied. Ongoing research and development focus on differentiation factors and tissue protection. In search for sources of autologous cells which are easier to collect and which may serve for more complex tissues like osteochondral implants, mesenchymal stem cells are investigated. The design of in vitro experiments, which are required for these investigations, has produced tissue engineering technologies, which may serve for pathophysiology research in inflammatory joint diseases and for exploration of treatment strategies. These together with the advances in biological therapies of rheumatic diseases are the basis of new concepts, which promise application of tissue engineering also in inflammatory joint diseases.

Autologous chondrocyte implantation of the knee: multicenter experience and minimum 3-year follow-up.

OBJECTIVE: To determine clinical outcome and graft survivorship in patients undergoing autologous chondrocyte implantation (ACI) for the repair of chondral defects of the knee. DESIGN: Prospective cohort study. SETTING: 19 centers in the United States. PATIENTS: 50 patients (37 males, 13 females). Mean age was 36 years (range: 19-53). Defects were grade III or IV with a mean size of 4.2 cm 2. All patients had a minimum of 36 months postoperative follow-up. MAIN OUTCOME MEASUREMENTS: Clinician and patient evaluation based on the modified Cincinnati Knee Rating System. Graft failure was defined as replacement or removal of the graft due to mechanical symptoms or pain. RESULTS: Clinician and patient evaluation indicated median improvements of 4 and 5 points, respectively, at 36 months following ACI (p < 0.001). Previous treatment with marrow stimulation techniques and size of defect did not impact the results with ACI. The most common adverse events reported were adhesions and arthrofibrosis and hypertrophic changes. Three patients had graft failure and required reimplantation or treatment with alternative cartilage repair techniques. Kaplan-Meier estimated freedom from graft failure was 94% at 36 months postoperatively (95% CI = 88-100%). CONCLUSIONS: These results of this study indicate excellent graft survivorship using ACI as well as substantial improvement in functional outcome.

[Autologous chondrocyte transplantation for treatment of cartilage defects of the knee joint. Clinical results]. / Die autologe Chondrozyten-Transplantation zur Behandlung von Knorpeldefekten des Kniegelenkes. Klinische Ergebnisse.

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.

Arthroscopic management of osteochondral lesions of the talus: results of drilling and usefulness of magnetic resonance imaging before and after treatment.

Since the advent of operative ankle arthroscopy and magnetic resonance imaging (MRI) specific treatment of osteochondritis dissecans of the talus has progressed rapidly. Drilling is still the treatment of choice in early stages of osteochondritis dissecans of the talus. Rear-entry guides and preoperative planning with MRI have led to better results with this kind of treatment. Within 5 years, 42 patients (26 male and 16 female) underwent arthroscopic treatment of osteochondritis dissecans of the talus, 22 underwent percutaneous drilling, 13 cancellous bone grafting, 4 refixation, and 3 curettage. The average age of the patients was 28 years (range, 11 to 53 years). A clinical score system was used in a clinical and MRI follow-up of 19 of the patients with K-wire drilling. Up to 100 points are given in the categories pain, stability/insecurity, efficiency/pain-free walking distance, gait, differences in circumference, range of motion, and power. There was a history of trauma in 31 of the 42 patients. The majority of lesions (24 cases) were localized at the lateral talus, and these patients all had trauma. In 11 of the 18 lesions at the medial talus, there was no evidence of trauma. The 19 patients in the follow-up achieved an average of 87 points. K-wire drilling represents the chief component of early stages with intact or partially fractured cartilage surface, whereas arthroscopically controlled cancellous bone grafts after curettage are used in grade II stages only. Results of K-wire drilling are not worse than those of cancellous bone grafts; this is attributable to a generous perforation of the sclerosis. This has contributed to an improved preoperative diagnosis with MRI.

The operative treatment of full thickness cartilage defects in the knee joint with autologous chondrocyte transplantation.

OBJECTIVE: The high clinical and socio-economical impact of cartilage defects and chondral degeneration is well-known. After trauma or without a known etiology, often young patients suffer from pain and a loss of function leading into a decrease of physical activity and, more severe, into long term disability and unemployment. The clinical use of autologous chondrocyte transplantation was introduced in 1994 reporting the data of a pilot study. The objective of this study is to evaluate the efficacy of this method of surgery. METHODS: Autologous chondrocyte transplantation has been established in our department since 1995 for the treatment of large, full thickness cartilage defects which can be completely covered with hyaline-like cartilage without harming the subchondral bone plate. Our first patients (n=24) all showed Grade IV lesions and an average defect size of 6.27 cm2. All but 4 of the patients had at least 1 cartilage defect related operation on the knee. RESULTS: The patients and the clinicians rating indicated an increase of a modified Cincinnati Knee score from 3.6 point pre-operation to 6.9 points after 6 months and 8.1 points at 12 months on a scale from 1 (bad) to 10 (excellent). These results support the data of an international multicenter study with almost 2000 patients. The 5 year results described by the originate authors are good to excellent in 85%-95% with an adverse event rate of 5%. CONCLUSION: Autologous chondrocyte transplantation has to be considered a safe and effective method for the treatment of large full thickness cartilage defects. Alternative treatments are symptomatical: drilling, abrasion, lavage, chondroplasty, or osteotomies. The short term results are promising but a lot of patients have to be treated for osteoarthritis as a consequence of failure with total joint arthroplasty. Osteochondral transplantations have the disadvantage of limited harvesting sites and the impairment of the subchondral bone plate.

[Clinical and cell biology aspects of autologous chondrocytes transplantation]. / Klinische und zellbiologische Aspekte der autologen Chondrozytenimplantation.Methode, Indikationen und wissenschaftliche Ergebnisse.

The treatment of deep cartilage defects is a challenge for every orthopaedic surgeon. The potential for regeneration of cartilage tissue is minimal and leads to mechanically inferior fibrous tissue. The established techniques induce the growth of fibrous tissue but fail to prevent arthrosis. Autologous chondrocyte transplantation seems to be the most promising therapy concept with clinical relevance to reserves a full thickness cartilage defect with hyaline-like cartilage. Outcome studies with a follow up from 2-10 years show in up to 90 % good and excellent results for defects on the femoral condyle and 70 % for the patella. Mechanical testing of the regenerated cartilage showed almost similar stiffness as nearly normal hyaline cartilage. The available data justify the acceptance of autologous chondrocyte transplantation as a standard procedure for limited indications and well-trained surgeons. Result of already inaugurated studies will show the potential of chondrocyte transplantation to prevent osteoarthritis.

Postoperative ossifications of the shoulder. Incidence and clinical impact.

Periarticular ossifications of the shoulder after surgery have been described since the beginning of the century. Risk factors and the clinical impact of heterotopic bone formation have been discussed controversially. After open surgery on the shoulder, 131 patients (rotator cuff repair n = 106, acromioplasty n = 25) were included in a retrospective study if pre- and postoperative X-rays were available. The age of the 90 men and 41 women averaged 51 years (range 29-67 years). The minimum follow-up was 2 years. Also, 108 patients were interviewed by questionnaire to estimate the subjective outcome of the procedure (5 patients were reported dead). A clinical examination was carried out on 86 patients using the Constant score for evaluation of the objective outcome. Heterotopic ossifications were found in 35 cases (26.7%), 28 of them after rotator cuff reconstruction and 7 after acromioplasty. A good to excellent result was reported by 89% (n = 65) of the patients without and by 80% (n = 28) of the patients with ossifications. The Constant score averaged 69 points and 74 points (n = 60), respectively. A significant difference between the two collectives could not be calculated. As significant risk factors for the formation of heterotopic bone, the existence of osteoarthritis and the duration and complexity of the procedure could be cited. The appearance of periarticular ossifications after surgery of the shoulder seems to be of minor clinical impact. Severe cases with major functional deficits should and can be prevented by a fast and atraumatic operation technique.

[Arthroscopic therapy of osteochondrosis dissecans of the talus--follow-up with a new "Ankle Score"]. / Arthroskopische Therapie der Osteochondrosis dissecans des Talus--Nachuntersuchung mit einem neuen "Ankle Score".

INTRODUCTION: Since the advent of operative ankle arthroscopy specific treatment of osteochondritis dissecans of the talus underwent rapid progress. Besides optimizing well-known methods as drilling, spongeous plastic, curettage or refixation of dissecates new trends go to transplantation of cultivated cartilage and osteochondral allografts. Previous follow-up examinations suffer on the one hand from partially small numbers of cases, on the other hand comparisons are difficult because so far no rating system of the function of the upper ankle does exist. MATERIAL AND METHODS: Within three years 34 patients underwent arthroscopic treatment of osteochondritis dissecans of the talus, 16 with percutaneous drilling, 12 spongeous plastics, three refixations and three curettages. The average age of the 22 men and 12 women was 25 years (11-48 years). A newly developed score system and a follow up MRI was used in a follow-up of 29 of the patients. Up to 100 points are given in the categories pain, stability/insecurity, efficiency/painfree walking distance, gait, differences in circumference, motility and power. RESULTS: 27 of the 34 patients had a trauma history. 20 lesions were localized at the lateral talus, they all had a trauma history. In 7 of the 14 lesions at the medial part of the talus there was no evidence of trauma. The 29 patients in the follow-up achieved an average of 87 points, the 16 patients after K-wire drilling 85 points and the 12 patients after spongeous plastic 90 points. Deductions were noted likewise in the subjective and objective parameters. 100 points were reached by 4 patients. DISCUSSION: Cultured chondrozytes and osteochondral grafts are new trends in treatment of osteochondritis dissecans while arthroscopically controlled spongeous plastic after curettage and K-wire drilling represent the main component of early stages with intact or partially fractured cartilage surface. Results of K-wire drilling are negligible worse than those of spongeous plastic, which is attributed to a generous perforation of the sclerosis. This is contributed to an improved preoperative diagnosis with MRI.