Scaffold-assisted cartilage tissue engineering using infant chondrocytes from human hip cartilage.

OBJECTIVE: Studies about cartilage repair in the hip and infant chondrocytes are rare. The aim of our study was to evaluate the use of infant articular hip chondrocytes for tissue engineering of scaffold-assisted cartilage grafts. METHOD: Hip cartilage was obtained from five human donors (age 1-10 years). Expanded chondrocytes were cultured in polyglycolic acid (PGA)-fibrin scaffolds. De- and re-differentiation of chondrocytes were assessed by histological staining and gene expression analysis of typical chondrocytic marker genes. In vivo, cartilage matrix formation was assessed by histology after subcutaneous transplantation of chondrocyte-seeded PGA-fibrin scaffolds in immunocompromised mice. RESULTS: The donor tissue was heterogenous showing differentiated articular cartilage and non-differentiated tissue and considerable expression of type I and II collagens. Gene expression analysis showed repression of typical chondrocyte and/or mesenchymal marker genes during cell expansion, while markers were re-induced when expanded cells were cultured in PGA-fibrin scaffolds. Cartilage formation after subcutaneous transplantation of chondrocyte loaded PGA-fibrin scaffolds in nude mice was variable, with grafts showing resorption and host cell infiltration or formation of hyaline cartilage rich in type II collagen. Addition of human platelet rich plasma (PRP) to cartilage grafts resulted robustly in formation of hyaline-like cartilage that showed type II collagen and regions with type X collagen. CONCLUSION: These results suggest that culture of expanded and/or de-differentiated infant hip cartilage cells in PGA-fibrin scaffolds initiates chondrocyte re-differentiation. The heterogenous donor tissue containing immature chondrocytes bears the risk of cartilage repair failure in vivo, which may be possibly overcome by the addition of PRP.

[Conservative therapy of osteoarthritis]. / Konservative Therapie der Gonarthrose.

Osteoarthritis of the knee is a degenerative joint disease with progressive degradation of articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking and joint effusion depending on the stage of the disease. In an effort to delay major surgery, patients with knee osteoarthritis are offered a variety of nonsurgical modalities, such as weight loss, exercise, physiotherapy, bracing, orthoses, nonsteroidal anti-inflammatory drugs (NSAIDs) and intra-articular viscosupplementation or corticosteroid injection. In general, the goals of these therapeutic options are to decrease pain and improve function. Some of these modalities may also have a disease-modifying effect by altering the mechanical environment of the knee. Chondroprotective substances, such as lucosamine, chondroitin sulphate and hyaluronic acid are safe and provide short-term symptomatic relief while the therapeutic effects remain uncertain.

Cartilage repair approach and treatment characteristics across the knee joint: a European survey.

INTRODUCTION: To describe indication, approach and treatment modalities for the management of knee cartilage lesions among a selected European population. METHODS: An electronic questionnaire covering general and specific items concerning cartilage repair at the knee joint was designed and disposed to survey cartilage treatment characteristics among a defined population of trained and accredited musculoskeletal surgeons. RESULTS: A total of 242 (80.13%) interviewees returned the questionnaire. Two-thirds of the respondents considered patient age to not limit (33.1%) or considered the age of 50 as the upper limit (32.2%) for interventional cartilage surgery. There was no consensus on when to correct mechanical axis deformation. Irrespective of lesion size, surgical debridement and microfracture are the techniques most frequently used. Surgical approach to full-thickness cartilage defects is commenced when the lesion size exceeds 1 cm(2) in 75.6% of respondents; mainly utilizing microfracture or debridement for defects smaller than 1, 2 and 3 cm(2). Controversy exists for treatment of lesions exceeding 3 cm(2), where autologous chondrocyte transplantation is utilized in the majority of cases (33.5%), while as well microfracture (19.0%) and with lesser frequency osteochondral plug (9.5%) transplantation are recommended. Debridement was indicated to be used in combination with other techniques, while microfracture, chondrocyte or osteochondral plug transplantation are applied as individual techniques. CONCLUSIONS: Microfracture with debridement are the two most frequently used operations in lesions up to 3 cm(2). There remains disagreement when indicating cartilage repair when age, mechanical axis deviation or treatment of lesions over 3 cm(2) are concerned.

[Operative treatment of cartilage lesions in the knee joint]. / Chirurgische Therapieverfahren zur Behandlung umschriebener Knorpelschäden am Kniegelenk.

With regard to the current demographic changes in today's population and the increasing demands of the patients i. e. in sports activity, the operative treatment of chondral lesions gained of importance in recent years. The treatment of cartilage injuries is not only of great importance in order to reduce the patients' symptoms, but also intends to avoid the appearance of secondary arthrosis. There are several different techniques available for the treatment of full-thickness defects (such as microfracture and autologous chondrocyte implantation), some of them following related principles. The choice of the optimal treatment technique remains of great importance and represents one of the major responsibilities of the surgeon in order to achieve optimal results. The current article represents a review of current techniques and developments in operative cartilage repair of the knee joint and gives help in the decision-making process, since the use of the appropriate technique becomes more and more important in order to achieve optimal clinical results.

Comparison of total and partial traumatic tears of the subscapularis tendon.

We treated surgically 16 shoulders with an isolated traumatic rupture of the subscapularis tendon over a six-year period. Nine patients had a total and seven a partial tear of the subscapularis tendon. Repair was undertaken through a small deltopectoral groove approach. The mean Constant score improved in total tears from 38.7 to 89.3 points (p = 0.003) and in partial tears from 50.7 to 87.9 points (p = 0.008). The total tears were significantly more improved by surgery than the partial tears (p = 0.001). The delay between trauma and surgery was inversely proportional to the improvement in the Constant score suggesting that early diagnosis and surgical repair improves outcome.

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.

[Arthroscopic resection of the acromioclavicular joint]. / Arthroskopische Resektion des Akromioklavikulargelenks.

OBJECTIVE: Arthroscopic resection of the painful and degenerative altered acromioclavicular (AC) joint without destabilization of the joint and therefore pain relief and improvement in function. INDICATIONS: Conservative failed therapy of painful AC joint osteoarthritis. Impingement caused by caudal AC joint osteophytes. Lateral clavicular osteolysis. CONTRAINDICATIONS: General contraindications (infection, local tumor, coagulation disorders), higher grade instability of the AC joint (resection only together with stabilization). SURGICAL TECHNIQUE: Diagnostic glenohumeral arthroscopy. Treatment of accompanying lesions (subacromial impingement, rotator cuff, long head of biceps). Subacromial arthroscopy with bursectomy (partial) and visualization of the AC joint. Resection of caudal osteophytes. Localization of the anterior portal using a spinal needle in the outside-in technique. Resection of 2-3 mm of the acromial side and the 3-4 mm of the clavicular side with shaver/acromionizer. RESULTS: An isolated open AC joint resection was performed in 9 studies and an arthroscopic resection in 6 studies. Good and very good results were obtained in 79% (range 54-100%) in open resection and 91% (range 85-100%) in arthroscopic resections. Patients were able to return to activities of daily life more quickly after arthroscopic resections than after open surgery.

[Arthroscopically assisted therapy of avascular necrosis of the femoral head]. / Arthroskopisch gestützte Behandlung der aseptischen Hüftkopfnekrose.

OBJECTIVE: Preservation of the hip joint function by treatment of the avascular necrosis of the femoral head in adults or at least avoiding progression. INDICATIONS: Avascular necrosis of the femoral head in adults in Steinberg stages I-III. In patients with Steinberg stage IVa (subchondral collapse ≤ 15% of the articular surface, depression < 2 mm) hip joint salvage therapy in early stages of femoral head collapse. CONTRAINDICATIONS: Manifest osteoarthritis of the hip joint. Joint infection. Relative contraindications: subchondral collapse > 15% of the articular surface or depression > 2 mm (Steinberg stage IVb and above). Persisting risk factors for a progression of avascular necrosis (e.g., alcohol abuse, chemotherapy, local irradiation, high-dose cortisone therapy) and obesity (BMI > 40). SURGICAL TECHNIQUE: Arthroscopy of the hip joint in case of cartilage defects and/or potential collapse of the femoral head. Without collapse of the femoral head and absence of severe damage of the cartilage: core decompression using a guiding sleeve through a lateral approach (Steinberg II, III). Subsequently curettage of the necrotic area through a central drill hole and insertion of autogenic bone cylinders using an OATS harvester (Steinberg II b/c, III b/c). In Steinberg stage IVa, reconstruction of the outline of the femoral head is attempted by reduction of the impressed portion (under intraoperative fluoroscopy). POSTOPERATIVE MANAGEMENT: Limited weight bearing (10 kg) of the operated leg for 6 weeks. In cases of large necrotic defects located directly beneath the subchondral bone (Steinberg IIIc) as well as subchondral collapse with flattening of the femoral head (Steinberg IVa) limited weight bearing (10 kg) for 12 weeks. RESULTS: Early results of femoral head preserving therapy in 53 patients (56 hips, consecutively treated between June 2004 and December 2009) after 33 ± 20 months: success rate (no arthroplasty, no reoperation, no radiological progress associated with clinical symptoms) 86% for patients treated with Steinberg stages I-III. Failure of the head preserving therapy with concern to the mentioned criteria depending on the initial Steinberg stage: 0 (0%) for stage I, 2 (10%) for stage II, 3 (25%) for stage III, and 4 (31%) for stage IVa.

[Sports activity and proprioceptive ability after arthroscopic capsulolabral repair of post-traumatic shoulder instability]. / Sportfähigkeit und propriozeptive Fähigkeiten nach arthroskopischer Kapsel-Labrum-Rekonstruktion bei posttraumatischer Schulterinstabilität.

AIM: The aim of the study was to evaluate the clinical and functional outcome after arthroscopic transglenoid stabilisation of post-traumatic shoulder instabilities. Besides assessing the sports activity level, a special emphasis was put into evaluating the proprioceptive ability in a clinical-experimental setting as well as comparisons with a control group. METHOD: We evaluated the functional results of 35 patients after arthroscopic stabilisation of post-traumatic, unidirectional anterior shoulder instabilities at a mean of 47.4 +/- 12.8 months postoperatively. Criteria such as subjective level of contentedness, range of motion, stability and sports activity as well as the Constant and Rowe scores were recorded. Joint position sense was assessed in 30 degrees internal and external rotation with the passive angle reproduction test using an inclinometer. The difference between the discerned and the target joint position was used as a measure of proprioceptive ability. Results were compared to the contralateral shoulder as well as to a control group consisting of 31 volunteers without any history of shoulder pain or injury. The Mann-Whitney U-test was used for statistical analysis. RESULTS: The level of subjective satisfaction on a visual analogue scale was 9.3 +/- 1.1 points. ROM testing showed a mean loss of 4.8 +/- 5.1 degrees of external rotation compared to the contralateral shoulder. A mean Constant score of 88.9 +/- 7.8 and a mean Rowe score of 86.7 +/- 19.0 points were obtained. Four patients had a reluxation of the shoulder, in 3 cases due to an adequate traumatic event. 20 of 24 athletes (83 %) were able to return to their previous sports activity level without any restrictions. Passive angle reproduction testing showed no significant difference regarding the proprioceptive ability between operated shoulders in internal and external rotation (mean angle difference IRO = 2.6 +/- 1.4 degrees , ARO = 3.3 +/- 1.5 degrees ) compared to the contralateral shoulder (2.9 +/- 1.5 degrees , 3.6 +/- 1.8 degrees , p = 0.56/0.36) as well as compared to the control group (3.0 +/- 1.1 degrees , 3.4 +/- 1.1 degrees , p = 0.67/0.32). CONCLUSIONS: The results of this study indicate that arthroscopic transglenoid shoulder stabilisation is a sufficient technique for the treatment of post-traumatic shoulder instability. Arthroscopic capsulolabral reconstruction led to a complete restoration of the proprioceptive ability in internal and external rotation. 83 % of the patients were able to return to their preoperative sports activity level.

Evaluation of Singh index for assessment of osteoporosis using digital radiography.

Evaluation of Singh index (SI) as a simple means for estimating bone mass on radiographs has been subject of numerous studies. All of these studies used plain film radiographs for assessment of SI. Digital radiography may improve validity and reliability of SI assessment. Aim of this study was to evaluate SI gradings assessed on digital radiographs. Digital pelvic radiographs of 100 patients were graded using SI by five independent observers (two radiologists, three traumatologists) blinded to dual energy X-ray absorptiometry (DXA) results and re-graded by all observers for assessment of intraobserver agreement. SI was correlated with DXA measurements and after grouping the patients according to World Health Organisation (WHO) criteria (osteoporosis, osteopenia, normal). Logistic regression analysis was performed in order to identify influential parameters on the SI grading process. Mean intraobserver agreement was 0.648+/-0.18 (Kendall's Tau) and 0.43+/-0.28 (kappa). Mean interobserver agreement was 0.488+/-0.193 (Kendall's Tau) and 0.199+/-0.248 (kappa). Mean correlation between SI and trochanteric BMD and T scores was 0.219+/-0.04 and 0.210+/-0.05 (Spearman's coefficient). Only one observer (senior radiologist) reached the significance level after grouping the patients' DXA results according to WHO criteria and correlating the results with SI gradings. Logistic regression analysis revealed a significant influence of trochanteric T score in two observers while other variable parameters failed to reach the significance level. Even though we found reasonable intraobserver agreement assessment of SI is highly subjective and interobserver agreement is generally poor. Moreover, using digital radiography could not improve correlation with DXA measurements.

Marrow stimulation techniques.

Due to the very low intrinsic activity of human adult cartilage, healing of chondral and osteochondral defects in patients cannot be expected. In treating symptomatic cartilage damage, marrow stimulation methods belong to the most frequently used methods, along with autologous chondrocyte transplantation (ACT) and mosaicplasty. These arthroscopic procedures are generally easy and the marrow stimulation treatment costs relatively little. In recent years, Pridie drilling has been increasingly replaced by the microfracture technique. This modification relies on the same biological principles of promoting resurfacing with the formation of fibro-cartilaginous repair tissue. For the treatment of smaller cartilage defects (<2.5 cm(2)), microfracture still remains the first choice for treatment. The clinical results after microfracture in the knee are age dependent. Younger and active patients (<40 years) with smaller isolated traumatic lesions on the femoral condyles have the best long-term results. The deterioration of the clinical results begins after 18 months and is significantly more pronounced in older patients with defects on the patella-femoral joint and tibia. The inferior quality of the repair tissue, partially incomplete defect filling and new bone formation in the defect area seem to be limitations of these methods. The AMIC (autologous matrix induced chondrogenesis) technique was developed to enable treatment of larger defects by the application of a collagen Type III/I membrane (Geistlich Pharma, Wolhusen, Switzerland), in particular when cell-engaged procedures such as ACT cannot be used for financial reasons or because it is not indicated. AMIC seems to be particularly suitable for treating damaged retropatellar cartilage, which is an advantage because these defects can be hard to treat with standard microfracturing alone. The results of the ongoing studies are awaited to establish whether better results with this technology are achievable in the long term.

[Current treatment for cartilage damage in the patellofemoral joint]. / Aktuelle Behandlung des Knorpelschadens im Patellofemoralgelenk.

Joint cartilage damage in adults has practically no tendency to self healing. Symptomatic grade III/IV damage requires surgical treatment. There are special challenges involved in cartilage damage in the patellofemoral joint as the complicated biomechanics of the joint is often combined with dysplasia. All tissue regeneration measures are based on the recruitment of cells. The synovial cells available in the joint can be differentiated to fibrous cartilage under certain mechanical conditions; however, they cannot sufficiently fill in defects. Also the use of bone marrow cells for cartilage reconstruction only creates mechanically inferior fibrous cartilage (Pridie drillings, microfracture, AMIC). Presently only cultivated, autologous chondrocytes from the lab are available for a biomechanically high-quality reconstruction of the cartilage layer.The application of mesenchymal stem cells is a subject of extensive international research. However, the first experimental studies, after initial formation of cartilage, disappointingly show significant ossification. Essential conditions for a successful treatment of patellofemoral cartilage damage are the diagnosis of accompanying pathological conditions, selection of the right cartilage-regenerating procedure, sufficient removal of the basic pathological defect, and implementation of standardized rehabilitation.

Tibial wedge osteotomy for osteochondral transplantation in talar lesions.

Between 1999 and 2002, 16 patients with osteochondral lesions on the central and posterior talar dome underwent osteochondral autografting. A new approach with temporary removal and replacement of a tibial bone block from the anterior tibial plafond was adopted. Inclusion criteria were joint stability, an age between 18 and 50 years, and osteochondral lesions stages 3 and 4 according to the radiological classification of Loomer, for which previous arthroscopic treatment was not successful. All patients underwent clinical and MRI evaluation after 12, 35 and 59 months. The AOFAS Ankle Hindfoot score improved significantly between the preoperative period and 1 year (p < 0.001), between 1 and 3 years (p < 0.001), but not between 3 and 5 years postoperative (p = 0.37). The score was independent from patients gender (p = 0.44) and age. The Spearman coefficient of correlation between clinical outcome and defect size was - 0.79 (p = 0.01), indicating that patients with small lesions had the best results. Control radiographs and MRIs showed no reduced joint space and good integration of the tibial bone block without incongruency. Osteochondral grafting with temporary removal of a tibial bone block is a successful technique with good midterm results in osteochondral talar lesions for which arthroscopic excision, curettage and drilling has failed.

Monteggia fractures in adults: long-term results and prognostic factors.

The objective of this retrospective study was to correlate the Bado and Jupiter classifications with long-term results after operative treatment of Monteggia fractures in adults and to determine prognostic factors for functional outcome. Of 63 adult patients who sustained a Monteggia fracture in a ten-year period, 47 were available for follow-up after a mean time of 8.4 years (5 to 14). According to the Broberg and Morrey elbow scale, 22 patients (47%) had excellent, 12 (26%) good, nine (19%) fair and four (8%) poor results at the last follow-up. A total of 12 patients (26%) needed a second operation within 12 months of the initial operation. The mean Broberg and Morrey score was 87.2 (45 to 100) and the mean DASH score was 17.4 (0 to 70). There was a significant correlation between the two scores (p = 0.01). The following factors were found to be correlated with a poor clinical outcome: Bado type II fracture, Jupiter type IIa fracture, fracture of the radial head, coronoid fracture, and complications requiring further surgery. Bado type II Monteggia fractures, and within this group, Jupiter type IIa fractures, are frequently associated with fractures of the radial head and the coronoid process, and should be considered as negative prognostic factors for functional long-term outcome. Patients with these types of fracture should be informed about the potential risk of functional deficits and the possible need for further surgery.

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.

Stress fractures in the juvenile skeletal system.

Stress fractures affecting the juvenile skeletal system are rare and are described as having a good prognosis. Precisely because these fractures are so rare, studies allowing clear and generally applicable conclusions are lacking. The object of the present study was a systematic analysis of patients with stress fractures in an immature skeletal system, with special reference to the frequently difficult and delayed diagnosis and to the forms of therapy considered appropriate. Twenty-five patients with a total of 27 stress fractures affecting bones with the growth plates still open were examined according to a standardized procedure. The average duration of follow-up was 4.8 years (SD +/- 2.3) and the average age at occurrence 12.9 years (SD +/- 4.31). The risk factors were largely the same as those in adults. The most frequent site was the tibia (48% of cases; n = 13), followed by the metatarsal bones. Most (26/27) fractures were treated conservatively, with an average duration of therapy of 8.9 weeks (SD 8.2 weeks). Ultimately, 17 (63%) of the fractures healed in such a way as to allow the patients to return to full athletic activity with no restrictions within 3 months after diagnosis. In 9 cases (33%) it was not possible to achieve complete absence of symptoms within 12 months after diagnosis was made. No pseudarthroses were observed. There was a significant correlation between clinical outcome recorded as "free of symptoms" and an early diagnosis (less than 2 weeks after first symptoms (p = 0.033) and a fracture line seen on MR tomography in contrast to a stress reaction with merely increased signal intensity (p = 0.037). Overall, a strikingly high proportion of these patients had a prolonged course. This is attributable partly to the delay in diagnosis and to inappropriate initial treatment. When stress fractures were recognizable by a demonstrable fracture line--in contrast to just an edema--on MR tomography and their diagnosis was followed by an adequate form of therapy the chances of complete healing seemed to be better. It is essential to carry out targeted imaging investigations, e.g., by means of MR tomography, when there is a reason to consider a stress reaction. Furthermore, stress fractures should be adequately treated until all symptoms have disappeared.

Subchondral and trabecular bone remodeling in canine experimental osteoarthritis.

INTRODUCTION: We wanted to test the hypothesis that quality changes occur in early-stage arthritic subchondral cancellous bone after acute subchondral damage. So far, not much attention has been paid to changes of the subchondral bone after traumatic subchondral lesions. MATERIALS AND METHODS: With an established animal model, we produced pure subchondral damage without initial affection of the articular cartilage in 12 Beagle dogs under MRI and histological control. We utilized bone histomorphometry to evaluate bone turnover, its structure and the articular cartilage 6 months after the initial damage. RESULTS: On follow-up, bone remodelling was indicated, e.g. by a significant increase in the trabecular bone volume and thickness, osteoblast number and osteoid surface and a decrease in the trabecular number in all 12 samples. Several other parameters showed a tendency, e.g. osteoblast surface and osteoclast number. Cartilage analysis showed degenerative changes in ten of 12 samples that had not shown any evidence of damage during the initial examination. DISCUSSION: Our investigation indicates a significant deterioration in the architecture of the cancellous bone with degenerative changes of the overlying articular cartilage after subchondral lesions, which change the mechanical properties.

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.

Transplantation of mesenchymal stromal cells on mineralized collagen leads to ectopic matrix synthesis in vivo independently from prior in vitro differentiation.

BACKGROUND: Tissue engineering using mesenchymal stromal cells (MSC) represents a promising approach for bone regeneration. Nevertheless, the optimal constructs have yet to be determined. It still remains unclear if there is a benefit of in vitro differentiation of MSC prior to transplantation or if undifferentiated MSC hold the optimal potential concerning new tissue formation. METHODS: After isolation and in vitro expansion, MSC were seeded on mineralized collagen sponges and transplanted in a heterotopic SCID mice model (n=12). While group A contained undifferentiated MSC, in group B cells were cultivated for 14 days in vitro under osteogenic conditions prior to implantation. Results were compared with non-loaded scaffolds (group C). Animals were killed for investigation at 4 and at 8 weeks. RESULTS: In situ hybridization demonstrated integration of MSC for up to 8 weeks in groups A and B. Histology revealed significantly more extracellular matrix synthesis in MSC-seeded scaffolds containing calcium phosphate and collagen type I at 4 and 8 weeks after transplantation compared with unloaded controls. At a biochemical level, higher levels of specific alkaline phosphatase expression were detected in MSC-loaded scaffolds (P<0.05). Scaffolds containing undifferentiated and differentiated MSC did not appear to differ in terms of matrix synthesis and protein expression, while the number of avital cells was significant higher in those probes loaded with differentiated MSC (P<0.01). DISCUSSION: The integration of transplanted cells and MSC-associated matrix synthesis encourages the use of MSC-loaded mineralized collagen for tissue engineering of bone. Furthermore, our data suggest that in vitro differentiation of MSC does not have a positive influence in terms of improved matrix synthesis.