Viability of loose body fragments in osteochondritis dissecans of the knee. A series of cases

Comparing telomere lengths in chondrocytes from intact cartilage and those isolated from loose bodies

INTRODUCTION

Given the intrinsic connection between telomeres, cell replication, and aging, telomere length serves as a valuable biomarker for evaluating cell quality and viability. Studying telomeres can offer vital insights into the suitability of cells within articular loose bodies for autologous chondrocyte implantation in treating chondral lesions. The aim of this study was to assess cell quality by analyzing telomere profiles in isolated cells from loose bodies.

METHODS

Chondrocytes from loose bodies and intact cartilage from 3 patients with osteochondritis dissecans who underwent a High Density-Autologous Chondrocyte Implantation (HD-ACI), were isolated and cultured. Telomere length was determined by High-Throughput Quantitative Fluorescence in situ Hybridization (HT-Q-FISH). Percentile of telomere length, percentages of telomere length values (QuantiTel), percentages of cells with specific telomere values (QuantiCell) were estimated in each sample.

RESULTS

Percentile and QuantiTel showed lower telomere lengths in chondrocytes from loose bodies than in those from intact cartilage. QuantiCell demonstrated that the percentage of cells with shorter telomeres was higher in cells from loose bodies than in intact cartilage. Median telomere length was statistically higher in chondrocytes from intact biopsies than in loose bodies.

CONCLUSION

Chondrocytes isolated from loose bodies exhibits a telomere distribution shorter than those from intact cartilage.

In Vitro Evaluation of Lateral Femur Condyle Free Chondral Fragment Swelling after Soaking in Normal Saline

OBJECTIVE

After traumatic knee injuries, chondral fragments can avulse off bone with the progeny fragment becoming a loose body. The loose fragment may be larger than expected when trying to surgically repair the fragment back to its original site. The purpose of this study was to determine whether a loose chondral fragment from the lateral femur condyle would increase in size and weight after soaking in normal saline (NS) for 14 days.

DESIGN

Twelve 6-mm OAT (osteoarticular transfer) plugs were harvested from 6 cadaver knees on the lateral femoral condyle to simulate a chondral fragment. The chondral fragments were then placed inside an airtight specimen container with NS (0.9% sodium chloride) and were measured over 14 days.

RESULTS

After 14 days, the chondral fragments showed no increase in diameter as they measured an average of 5.567 ± 0.448 mm on Day 1 and 5.702 ± 0.253 mm on Day 14 (P = 0.183). The chondral fragments showed an increase in mass from an average of 0.058 ± 0.012 g on Day 1 to 0.073 ± 0.012 g on Day 14 (P < 0.001) and an increase in thickness from an average of 2.038 ± 0.346 mm on Day 1 to 2.229 ± 0.297 mm on Day 14 (P = 0.033).

CONCLUSIONS

Chondral fragments in NS increase in mass and thickness over time, but do not change in diameter. When surgeons are evaluating loose chondral fragments for fixation, they should consider that these fragments may appear thicker than the recipient location.

Patient-Specific iPSC-Derived Models Link Aberrant Endoplasmic Reticulum Stress Sensing and Response to Juvenile Osteochondritis Dissecans Etiology

Juvenile osteochondritis dissecans (JOCD) is a pediatric disease, which begins with an osteonecrotic lesion in the secondary ossification center which, over time, results in the separation of the necrotic fragment from the parent bone. JOCD predisposes to early-onset osteoarthritis. However, the knowledge gap in JOCD pathomechanisms severely limits current therapeutic strategies. To elucidate its etiology, we conducted a study with induced pluripotent stem cells (iPSCs) from JOCD and control patients. iPSCs from skin biopsies were differentiated to iMSCs (iPSC-derived mesenchymal stromal cells) and subjected to chondrogenic and endochondral ossification, and endoplasmic reticulum (ER)-stress induction assays. Our study, using 3 JOCD donors, showed that JOCD cells have lower chondrogenic capability and their endochondral ossification process differs from control cells; yet, JOCD- and control-cells accomplish osteogenesis of similar quality. Our findings show that endoplasmic reticulum stress sensing and response mechanisms in JOCD cells, which partially regulate chondrocyte and osteoblast differentiation, are related to these differences. We suggest that JOCD cells are more sensitive to ER stress than control cells, and in pathological microenvironments, such as microtrauma and micro-ischemia, JOCD pathogenesis pathways may be initiated. This study is the first, to the best of our knowledge, to realize the important role that resident cells and their differentiating counterparts play in JOCD and to put forth a novel etiological hypothesis that seeks to consolidate and explain previously postulated hypotheses. Furthermore, our results establish well-characterized JOCD-specific iPSC-derived in vitro models and identified potential targets which could be used to improve diagnostic tools and therapeutic strategies in JOCD.

Chondrocyte Isolation from Loose Bodies-An Option for Reducing Donor Site Morbidity for Autologous Chondrocyte Implantation

Loose bodies (LBs) from patients with osteochondritis dissecans (OCD) are usually removed and discarded during surgical treatment of the defect. In this study, we address the question of whether these LBs contain sufficient viable and functional chondrocytes that could serve as a source for autologous chondrocyte implantation (ACI) and how the required prolonged in vitro expansion affects their phenotype. Chondrocytes were isolated from LBs of 18 patients and compared with control chondrocyte from non-weight-bearing joint regions (n = 7) and bone marrow mesenchymal stromal cells (BMSCs, n = 6) obtained during primary arthroplasty. No significant differences in the initial cell yield per isolation and the expression of the chondrocyte progenitor cell markers CD44 + /CD146+ were found between chondrocyte populations from LBs (LB-CH) and control patients (Ctrl-CH). During long-term expansion, LB-CH exhibited comparable viability and proliferation rates to control cells and no ultimate cell cycle arrest was observed within 12 passages respectively 15.3 ± 1.1 mean cumulative populations doublings (CPD). The chondrogenic differentiation potential was comparable between LB-CH and Ctrl-CH, but both groups showed a significantly higher ability to form a hyaline cartilage matrix in vitro than BMSC. Our data suggest that LBs are a promising cell source for obtaining qualitatively and quantitatively suitable chondrocytes for therapeutic applications, thereby circumventing donor site morbidity as a consequence of the biopsies required for the current ACI procedure.

Loose Body Versus Trochlear Biopsy Matrix-Induced Autologous Chondrocyte Implantation (MACI) MOCART Scores and IKDC Reported Outcomes in Pediatric Patients

BACKGROUND

Matrix-induced autologous chondrocyte implantation (MACI) has shown promising results in the treatment of osteochondral lesions of the knee. A recent study showed similar viability comparing chondrocytes harvested from the intercondylar notch compared to those harvested from osteochondral loose bodies. However, there is limited evidence assessing how these different biopsies perform clinically. The goal of this study was to compare both radiographic and patient-reported outcomes in patients with patellar and femoral osteochondral lesions treated with MACI using either a standard intercondylar notch biopsy or an osteochondral loose body biopsy.

METHODS

A retrospective study was performed on all pediatric autologous chondrocyte implantation procedures performed from 2014 to 2017 at a single institution. Patients were divided into 2 groups: one group had cartilage derived from a standard intercondylar notch biopsy (n=9) and the other group had cartilage derived from an osteochondral loose body found within the ipsilateral knee (n=10). At a minimum of 1-year postimplantation, magnetic resonance imagings of the operative knee were performed and the Magnetic Resonance Observation of Cartilage Repair Tissue Knee Score (MOCART 2.0) knee score was used to assess the integrity and quality of the cartilage repair tissue. Interclass correlation coefficients were calculated between the 2 groups. International Knee Documentation Committee (IKDC) outcome scores were determined at a minimum 2 years post-implantation.

RESULTS

The interclass correlation coefficient between three independent examiners for the MOCART scoring was excellent at 0.94. With regards to the MOCART score, the loose body group had an insignificant 17-point lower median score at 63 [interquartile range (IQR): 58 to 89] compared to the intercondylar group at 80 (IQR: 65 to 90) ( P =0.15). There was no difference in IKDC scores with the loose body group having a median score of 82 (IQR: 65 to 95) and the intercondylar group having a median score of 84 (IQR: 53 to 99) ( P =0.90).

CONCLUSION

These results demonstrate that osteochondral loose bodies can be used as viable harvest site in MACI procedures with no difference in functional and radiographic outcomes at 2 years postimplantation. This may limit both short and long-term donor site morbidity.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Association of Subchondral Changes With Age and Clinical Outcome in Patients With Osteochondral Fractures in the Knee: MRI Analysis at 1 to 10 Years Postoperatively

Background:

Predictive factors influencing outcomes after surgical fixation of osteochondral fractures (OCFs) in the knee, particularly time between injury and surgery, have not been determined.

Purpose:

To report imaging and clinical outcomes after OCF fixation and to assess the association between clinical scores and patient characteristics, lesion morphology, and appearance on magnetic resonance imaging (MRI) scans.

Study Design:

Case series; Level of evidence, 4.

Methods:

We assessed the clinical and imaging outcomes of 19 patients after screw fixation for OCFs in the knee at a minimum follow-up of 1 year. Patient characteristics, lesion morphology, and time from trauma to surgery were reviewed for each patient. At final follow-up, patients completed a 100-point visual analog scale (VAS) for pain, Tegner activity scale, Knee injury and Osteoarthritis Outcome Score (KOOS), and patient satisfaction survey. Postoperative MRI scans were assessed using the MOCART (magnetic resonance observation of cartilage repair tissue), Osteochondral Allograft MRI Scoring System, and bone marrow edema (BME) size.

Results:

The mean patient age at surgery was 21.3 ± 11.4 years, and the median time from trauma to surgery was 10 days (range, 0-143 days). The refixed OCF fragment failed in 1 (5.3%) patient on the lateral condyle at 15 months postoperatively. The mean follow-up for the remaining 18 patients was 4.7 ± 3.2 years, and postoperative outcomes were as follows: VAS pain score, 9.5 ± 17.9; Tegner score, 4.8 ± 2.3; KOOS–Pain, 85.9 ± 17.6, KOOS-Symptoms, 76.4 ± 16.1; KOOS–Activities of Daily Living, 90.3 ± 19.0; KOOS–Sport, 74.4 ± 25.4; and KOOS–Quality of Life, 55.9 ± 24.7. Overall, 84.2% were satisfied or very satisfied with outcomes. Patient age was significantly associated with KOOS subscale scores and subchondral imaging parameters including BME and presence of subchondral cysts, which in turn were the only imaging variables linked to clinical outcomes (P < .05). Time from injury to surgery was not correlated with clinical or imaging outcomes.

Conclusion:

Fixation of OCFs yielded acceptable clinical and imaging outcomes at a mean 5-year follow-up with seemingly little influence of delayed surgical treatment. Postoperative subchondral changes were significantly associated with clinical outcomes and were linked to patient age at surgery.

Hybrid Treatment of Osteochondral Fracture of the Patella With Particulated Juvenile Cartilage and Fragment Fixation

Acute patellar dislocation can result in osteochondral fracture of the patella, resulting in multiple osteochondral fragments, with only one fragment able to be fixated into the defect effectively. In these cases, we propose a hybrid procedure to repair the defect using the fixation of one of the osteochondral fragments and particulated juvenile articulate cartilage to fill the remaining defect in the patella. This technique maximizes the amount of native articular surface that we can preserve on the patella. The use of fragment fixation in combination with particulated juvenile articulate cartilage will help prevent further articular damage to the patella and reduce the risk of developing osteoarthritis in patients suffering from an osteochondral fracture as a result of acute patellar dislocation.

Three-Year Outcomes After MACI for Glenoid Cartilage Loss in an Adolescent Athlete: A Case Report

CASE

We report the 3-year outcomes of a 14-year-old boy who anteriorly dislocated his shoulder playing football and suffered a 9-cm2 chondral defect of the anterior glenoid and subsequently treated with matrix-applied characterized autologous chondrocytes (MACI) of the defect with open labral repair.

CONCLUSION

The management of glenohumeral chondral lesions in adolescent patients remains a challenge. Our case of the successful treatment of a glenoid chondral defect with MACI offers hope as a potential treatment option for adolescent patients with this challenging problem.

Clinical and Radiographic Outcomes After Fixation of Chondral Fragments of the Knee in 6 Adolescents Using Autologous Bone Pegs

Background:

Little is known regarding the optimal treatment for displaced, purely chondral fragments in the knee.

Purpose:

To report the clinical and radiographic outcomes of chondral fragment fixation in adolescents through use of autologous bone pegs.

Study Design:

Case series; Level of evidence, 4.

Methods:

This retrospective, single-center study evaluated 6 patients (mean age, 12.9 years) who underwent fixation of chondral fragments (no visualized bone attached) using autologous bone pegs (mean postoperative follow-up, 5.2 years; range, 1.4-10.9 years). The causes were trauma (n = 5) and osteochondritis dissecans (n = 1). Lesions were located in the trochlear groove (lateral, n = 3; medial, n = 2) or posterior part of the lateral femoral condyle (n = 1). The mean lesion size was 3.8 cm² (range, 0.8-9.0 cm²). Patients were evaluated via physical examination and magnetic resonance imaging (MRI) using magnetic resonance observation of cartilage repair tissue scores.

Results:

In total, 5 patients successfully returned to sports without restrictions at a mean of 7 months (range, 6-8 months) postoperatively. At the latest follow-up, these 5 patients had full range of motion and no joint effusion. The mean magnetic resonance observation of cartilage repair tissue score was 85 (range, 70-95) at a mean duration of 3 years (range, 1-5 years). One patient experienced failure at 1.3 years postoperatively after a traumatic injury and subsequently underwent removal of the fixed fragment and a drilling procedure.

Conclusion:

In most adolescents, fixation of chondral fragments with no visualized bony portion using autologous bone pegs provided a satisfactory success rate and good healing of cartilage tissue confirmed on MRI scans.

Assessment of Cartilage Growth After Biopsy of Osteochondral Loose Bodies in Adolescent Knees for Use in Autologous Chondrocyte Implantation

BACKGROUND

The goal of this study is to determine whether harvested cartilage from an osteochondral loose body maintains the same viability for implantation as cartilage harvested from the traditional locations within the adolescent knee for autologous chondrocyte implantation (ACI).

METHODS

A retrospective study was performed on all ACI procedures performed from 2014 to 2017 at a single institution. Biopsies were derived from 2 groups: osteochondral loose body verses the intercondylar notch. The viability, yield, identity, potency, and density were obtained from each sample in addition to basic demographics and concomitant injuries. A total of 12 patients with osteochondral loose bodies 14.6 (SD=2.9) and 20 patients 13.6 (SD=3.3) with intercondylar notch biopsies were evaluated for the study.

RESULTS

In the microscopic and histologic comparison, there was no significant difference in viability: 94% in the loose bodies and 93% in the intercondylar notch groups, identity: 7.4 d5L versus 6.3 d5L, or yield. Minimum yield is presented as different units in Carticel (1.2×10 cells/vial) and matrix-induced ACI (>8500 relative fluorescent units) products; however, there was no difference between groups and all samples were above the acceptable limit. Minimum identity value is recorded as d5L> -2.00 and all samples were above this limit. In addition, no sample had signs of contamination or endotoxin in either group.

CONCLUSION

These results demonstrate an alternative method for obtaining cartilage biopsies in ACI procedures that may limit short-term and long-term donor site morbidity.

LEVEL OF EVIDENCE

Level III.

Human osteochondritis dissecans fragment-derived chondrocyte characteristics ex vivo, after monolayer expansion-induced de-differentiation, and after re-differentiation in alginate bead culture

BACKGROUND

Autologous chondrocyte implantation (ACI) is a therapy for articular cartilage and osteochondral lesions that relies on notch- or trochlea-derived primary chondrocytes. An alternative cell source for ACI could be osteochondritis dissecans (OCD) fragment-derived chondrocytes. Assessing the potential of these cells, we investigated their characteristics ex vivo and after monolayer expansion, as monolayer expansion is an integral step of ACI. However, as monolayer expansion can induce de-differentiation, we asked whether monolayer-induced de-differentiation can be reverted through successive alginate bead culture.

METHODS

Chondrocytes were isolated from the OCD fragments of 15 patient knees with ICRS grades 3-4 lesions for ex vivo analyses, primary alginate bead culture, monolayer expansion, and alginate bead culture following monolayer expansion for attempting re-differentiation. We determined yield, viability, and the mRNA expression of aggrecan and type I, II, and X collagen.

RESULTS

OCD fragment-derived chondrocyte isolation yielded high numbers of viable cells with a low type I:II collagen expression ratio (< 1) and a relatively high aggrecan and type II and X collagen mRNA expression, indicating chondrogenic and hypertrophic characteristics. As expected, monolayer expansion induced de-differentiation. Alginate bead culture of monolayer-expanded cells significantly improved the expression profile of all genes investigated, being most successful in decreasing the hypertrophy marker type X collagen to 1.5% of its ex vivo value. However, the chondrogenic phenotype was not fully restored, as the collagen type I:II expression ratio decreased significantly but remained > 1.

CONCLUSION

OCD fragment derived human chondrocytes may hold not yet utilized clinical potential for cartilage repair.

Articular Cartilage Repair of the Knee in Children and Adolescents

Articular cartilage predominantly serves a biomechanical function, which begins in utero and further develops during growth and locomotion. With regard to its 2-tissue structure (chondrocytes and matrix), the regenerative potential of hyaline cartilage defects is limited. Children and adolescents are increasingly suffering from articular cartilage and osteochondral deficiencies. Traumatic incidents often result in damage to the joint surfaces, while repetitive microtrauma may cause osteochondritis dissecans. When compared with their adult counterparts, children and adolescents have a greater capacity to regenerate articular cartilage defects. Even so, articular cartilage injuries in this age group may predispose them to premature osteoarthritis. Consequently, surgery is indicated in young patients when conservative measures fail. The operative techniques for articular cartilage injuries traditionally performed in adults may be performed in children, although an individualized approach must be tailored according to patient and defect characteristics. Clear guidelines for defect dimension–associated techniques have not been reported. Knee joint dimensions must be considered and correlated with respect to the cartilage defect size. Particular attention must be given to the subchondral bone, which is frequently affected in children and adolescents. Articular cartilage repair techniques appear to be safe in this cohort of patients, and no differences in complication rates have been reported when compared with adult patients. Particularly, autologous chondrocyte implantation has good biological potential, especially for large-diameter joint surface defects.

Viability of Cells From Displaced Fragments of the Elbow Osteochondritis Dissecans: Alternative Source of Autologous Chondrocyte Implantation

PURPOSE

To assess the histological properties of cells from displaced fragments obtained from patients with advanced osteochondritis dissecans (OCD) of the elbow and to examine whether these displaced fragments could be used as cell sources for autologous chondrocyte implantation.

METHODS

We harvested 6 displaced fragments from 6 patients who underwent osteochondral mosaicplasty for OCD of the elbow. The displaced fragments were examined histologically and digested to obtain chondrocytes. The cells obtained from young patients and skeletally matured cadaveric donors were examined using quantitative reverse transcription polymerase chain reaction analysis to quantify the expression of chondrocyte marker genes. The cells were cultured in atelocollagen, and the properties of 3-dimensional cultured cartilage were examined.

RESULTS

All 6 displaced fragments contained hyaline cartilage tissue. Chondrocyte marker genes were examined using cells from only 4 patients, because we obtained enough cells in only 4 patients. The relative expression levels of aggrecan, type II, Sox 9 were 2.61, 4.03, and 1.71, respectively. Three-dimensional cultured cartilage from all 6 displaced fragments contained 62.0 pg/cell (range, 22.8-91.3 pg/cell) of glycosaminoglycan and expressed type II collagen in the superficial and middle layer.

CONCLUSIONS

The chondrocytes obtained from the displaced fragments remained viable and exhibited chondrogenic features. These cells may potentially be a cell source of autologous chondrocytes implantation.

CLINICAL RELEVANCE

We have shown that displaced fragments from OCD of the elbow have potential for a cell source for generating 3-dimensional cultured cartilage.

The knee joint loose body as a source of viable autologous human chondrocytes

Loose bodies are fragments of cartilage or bone present in the synovial fluid. In the present study we assessed if loose bodies could be used as a source of autologous human chondrocytes for experimental purposes. Histochemical examination of loose bodies and differential enzymatic digestions were undertaken, the isolated cells were cultured in alginate bead microspheres and immunolocalisations were undertaken for chondrogenic markers such as aggrecan, and type II collagen. Isolated loose body cells had high viability (≥90% viable), expressed chondrogenic markers (aggrecan, type II collagen) but no type I collagen. Loose bodies may be a useful source of autologous chondrocytes of high viability.

Viability of Pathologic Cartilage Fragments as a Source for Autologous Chondrocyte Cultures

OBJECTIVE

To study if a culture of chondrocytes can be obtained from pathologic hyaline cartilage (PHC) fragments.

DESIGN

Twenty-five men and 9 women with osteochondritis dissecans (OCD) in 11 cases, arthrosis in 13 patients, and trauma in the remaining 10 cases were included. The PHC fragments and a small sample of the next healthy cartilage were extracted by arthroscopy. According to the appearance, the PHC samples were divided into fixed (3 cases), flapped (6 patients), or loose bodies (25 cases), depending on the attachment degree of the cartilage to the subchondral bone. Approximately half of each pathologic sample and the whole healthy one were digested to isolate the cells trying to establish the cell culture.

RESULTS

We were able to establish a cell culture in 7 out of 34 (20.6%) PHC samples (positive samples), whereas in the remaining 27 (79.4%) no cell growth was observed (negative samples). Most of the negative samples were loose bodies (P = 0.005) taken from patients with OCD or arthrosis (P = 0.001) with an evolution time of more than 1 year (P < 0.001). The best binary logistic regression model (P < 0.001) showed that the only factor affecting the establishment of cell culture was the evolution time (P = 0.044).

CONCLUSION

It is possible to culture chondrocytes from osteochondral fragments if they are traumatic, within a year of injury and not from fragments due to arthrosis or OCD.

Arthroscopic treatment of bony loose bodies in the subacromial space

INTRODUCTION

Multiple bony loose bodies in the subacromial space caused form cartilage or bone cells and continue to grow.

PRESENTATION OF CASE

A 58-year-old man with two-year history of swelling and pain of the right shoulder. He had no history of tuberculosis and rheumatoid arthritis. Magnetic resonance (MR) images showed some bony loose bodies in the subacromial space. The removal of loose bodies and bursa debridement were performed arthroscopically. Histological diagnosis of them was synovitis with fibrous bodies.

DISCUSSION

Extra-articular loose bodies is extremely rare, especially in the subacromial space, which maybe originated in the proliferative synovial bursa. Most authors recommend open removal to relive the pain, but there were choice to apply arthroscopy to remove them.

CONCLUSION

The mechanism of formation of bony loose bodies is not clear, may be associated with synovial cartilage metaplasia. Arthroscopic removal of loose bodies and bursa debridement is a good option for treatment of the loose body in the subacromial space, which can receive good function.

Treatment of juvenile osteochondritis dissecans of the talus: current concepts review

Juvenile osteochondritis dissecans of the talus (JODT) affects the subchondral bone primarily and, in a skeletally immature population, articular cartilage secondarily. It probably consists of aseptic bone necrosis whose spontaneous healing is impaired by microtraumas, resulting in an osteochondral injury and, in some cases, in osteoarthritis. In many cases the clinical presentation is asymptomatic. Mild chronic pain is frequent, sometimes accompanied by swelling, stiffness or locking. Few data are currently available on this topic and, moreover, most existing data were obtained from mixed groups and populations; it is therefore difficult to outline a scheme for the treatment of JODT. However, the most suitable treatment in the first stages of the disease is conservative. The presence of a loose body is an indication for surgical fixation, drilling or regenerative procedures, depending on the presence/extent of subchondral bone sclerosis and the surgeon's experience. Drilling has been shown to promote the healing of lesions with minimal surgical trauma. Microfractures, since they induce fibrocartilage repair, are to be considered only for small injuries. Mosaicplasty and osteochondral autograft transplantation may cause donor site morbidity and are techniques little reported in JODT. Regenerative techniques and fresh allografts give good results in osteochondral lesions, but further studies are required to describe the results that can be obtained in JODT alone.

Management strategies for osteochondritis dissecans of the knee in the skeletally immature athlete

SYNOPSIS

Osteochondritis dissecans (OCD) is a disorder resulting in focal breakdown of the subchondral bone, with potential disruption of the overlying articular cartilage. The femoral condyles of the knee are the most common locations for OCD, and the incidence of OCD appears to be increasing among active children. Juvenile OCD (JOCD) can be distinguished from adult OCD by the presence of open growth plates. Due to a lack of evidence on its early diagnosis, optimal treatment, and long-term course of healing, JOCD presents a unique challenge for the health care team. Approximately 50% to 67% of stable JOCD lesions heal successfully with nonoperative treatment. For unstable lesions and stable lesions that fail nonoperative treatment, a variety of surgical interventions can be utilized to stimulate bony healing and address articular cartilage lesions. It is recommended that rehabilitation of JOCD be tailored to the individual patient, based on the stage and radiographic status of the lesion and the mode of surgery employed when surgically addressed. Although there is a growing body of literature on this condition, the etiology and optimal methods for treatment, rehabilitation, and evaluating outcomes remain inconclusive due to a lack of quality evidence.

LEVEL OF EVIDENCE

Therapy, level 5.

Late-diagnosed large osteochondral fracture of the lateral femoral condyle in an adolescent: a case report

In this case report, we describe a large osteochondral fracture of the anterolateral femoral condyle in an adolescent athlete while dancing. At 3 months after the misdiagnosed injury, the condylar defect was covered by a layer of disorganized fibrous tissue rich in blood vessels. To achieve good repair, an accurate curettage of the fractured surfaces, a precise reduction, and a stable internal fixation of the fragments were performed. Two poly-L-lactic acid bioabsorbable screws were used to obtain appropriate compression. At the 2-year follow-up, the patient was asymptomatic and had resumed her previous dancing activity. An MRI scan showed no interruptions of the cartilage layer at the boundary with the healthy tissue, but cartilage thinning and extensive subchondral remodeling were detected.

Surgical management of osteochondritis dissecans of the knee

Osteochondritis dissecans of the knee primarily affects subchondral bone, with a secondary effect on the overlying articular cartilage. This process can lead to pain, effusions, and loose body formation. While stable juvenile lesions often respond well to nonoperative management, unstable juvenile lesions, as well as symptomatic adult lesions, often require operative intervention. Short-term goals focus on symptomatic relief, while long-term expectations include the hope of preventing early-onset arthritis. Surgical options include debridement, loose body removal, microfracture, arthroscopic reduction and internal fixation, subchondral drilling, osteochondral autograft or allograft transplantation, and autologous chondrocyte implantation. Newer single-stage cell-based procedures have also been developed, utilizing mesenchymal stem cells and matrix augmentation. Proper treatment requires evaluation of both lesional (size, depth, stability) and patient (age, athletic level) characteristics.

Osteochondritis dissecans of the knee in children and adolescents

PURPOSE OF REVIEW

Osteochondritis dissecans (OCD) of the knee is a well-described condition that can cause significant morbidity in children and adolescents; timely diagnosis is key to preventing compromise to the articular cartilage and maximizing opportunity to perform a restorative procedure. Juvenile OCD has a better prognosis than does adult OCD, with higher rates of spontaneous healing with conservative treatment. Still, there are certain indications for surgical restoration procedures. Controversies arise over when to decide surgical procedure and what is the best surgical treatment option in this young population.

RECENT FINDINGS

Some authors believe nonoperative management should be the first-line treatment for stable OCD lesions in children. The only consensus in regard to this modality is that, if a patient is truly asymptomatic or experiencing low-level symptoms, then the duration of nonoperative treatment should be at least 3-6 months before opting for operative treatment. In the case of failed nonsurgical management or in the setting of an unstable fragment, surgical intervention should be implemented. Recent published data suggest no difference in clinical or radiographic outcome when comparing different surgical techniques.

SUMMARY

OCD of the knee requires a timely diagnosis to maximize opportunity to perform a reparative procedure. Indications for surgical treatment are based on lesion stability, skeletal maturity, and clinical symptoms. Reestablishing the joint surface, improving the blood supply of the fragment, rigid fixation, and early motion are primary goals for osteochondral fragment preservation. When the fragment is not suitable for preservation, careful consideration of defect location and the patient's clinical presentation will determine when cartilage restoration procedures should be utilized.

Comparison between normal and loose fragment chondrocytes in proliferation and redifferentiation potential

PURPOSE

Loose fragments in osteochondritis dissecans (OCD) of the knee require internal fixation. On the other hand, loose fragments derived from spontaneous osteonecrosis of the knee (SONK) are usually removed. However, the difference in healing potential between OCD- and SONK-related loose fragments has not been elucidated. In this study, we investigated proliferative activity and redifferentiation potential of normal cartilage-derived and loose fragment-derived chondrocytes.

METHODS

Cells were prepared from normal articular cartilages and loose fragment cartilages derived from knee OCD and SONK. Cellular proliferation was compared. Redifferentiation ability of pellet-cultured chondrocytes was assessed by real-time PCR analyses. Mesenchymal differentiation potential was investigated by histological analyses. Positive ratio of a stem cell marker CD166 was evaluated in each cartilaginous tissue.

RESULTS

Normal and OCD chondrocytes showed a higher proliferative activity than SONK chondrocytes. Chondrogenic pellets derived from normal and OCD chondrocytes produced a larger amount of safranin O-stained proteoglycans compared with SONK-derived pellets. Expression of chondrogenic marker genes was inferior in SONK pellets. The CD166-positive ratio was higher in normal cartilages and OCD loose fragments than in SONK loose fragments.

CONCLUSIONS

The OCD chondrocytes maintained higher proliferative activity and redifferentiation potential compared with SONK chondrocytes. Our results suggest that chondrogenic properties of loose fragment-derived cells and the amount of CD166-positive cells may affect the repair process of osteochondral defects.

Microfracture for treatment of knee cartilage defects in children and adolescents

Even though operative microfracture is the most frequent method for treatment of limited knee joint cartilage lesions among adults, data about ouctome in children and adolescents are rare. We performed a retrospective chart review and telephone interview to analyze for the clinical outcome following knee joint cartilage defect microfracturing among 10 children. Mean postoperative Lysholm was 92.1±9.9 and Tegner was 7.0±1.9. Clinical outcome differed across knee joint regions, as well as in dependence of varying pre-operative symptom duration, although this was not significant. Regression analysis did not reveal a significant impact of patient or defect characteristics on clinical outcome. Arthroscopic microfracturing for treatment of limited size symptomatic knee joint cartilage defects among children and adolescents is considered a reasonable surgical option. However, long-term outcome and larger patient cohorts are required.

In vitro phenotypic modulation of chondrocytes from knees of patients with osteochondritis dissecans: implications for chondrocyte implantation procedures

We attempted to characterise the biological quality and regenerative potential of chondrocytes in osteochondritis dissecans (OCD). Dissected fragments from ten patients with OCD of the knee (mean age 27.8 years (16 to 49)) were harvested at arthroscopy. A sample of cartilage from the intercondylar notch was taken from the same joint and from the notch of ten patients with a traumatic cartilage defect (mean age 31.6 years (19 to 52)). Chondrocytes were extracted and subsequently cultured. Collagen types 1, 2, and 10 mRNA were quantified by polymerase chain reaction. Compared with the notch chondrocytes, cells from the dissecate expressed similar levels of collagen types 1 and 2 mRNA. The level of collagen type 10 message was 50 times lower after cell culture, indicating a loss of hypertrophic cells or genes. The high viability, retained capacity to differentiate and metabolic activity of the extracted cells suggests preservation of the intrinsic repair capability of these dissecates. Molecular analysis indicated a phenotypic modulation of the expanded dissecate chondrocytes towards a normal phenotype. Our findings suggest that cartilage taken from the dissecate can be reasonably used as a cell source for chondrocyte implantation procedures.

Osteochondritis Dessicans- Primary Fixation using Bioabsorbable Implants

INTRODUCTION

Osteochondritis dessicans (OCD) is a localized condition where a section of articular cartilage and underlying subchondral bone separate from the joint surface. It is important to diagnose unstable OCD early and fix the fragments primarily as the results of any surgical management at late presentations are guarded. Use of bioabsorbable implants for fixing OCD is recent and we report one such case in grade IV OCD.

CASE REPORT

We present a 14 year old girl who came with a history of acute pain, swelling, inability to bear weight on the right knee following a dance practice. MRI showed stage IV osteochondral fragment measuring 20x 8mm lying free. This was primarily fixed with bioabsorbable implants. 10 months follow up showed excellent clinical and functional results.

CONCLUSION

This case highlights the advantages of early primary fixation whenever possible. By far, to our knowledge, this is the first case of successful treatment of stage IV OCD using bioabsorbable implants.

Hybrid fixation: evaluation of a novel technique in adult osteochondritis dissecans of the knee

PURPOSE

Treatment of osteochondritis dissecans of the adult knee requires bone and cartilage integration of the loose fragment. Screw fixation provides primary stability but does not guarantee bony consolidation. Additional biological fixation using osteochondral grafts-hybrid fixation-could improve fragment integration.

METHODS

The study included seven patients [median age 21 years (15-29)] who underwent surgery for Bedouelle IIB or III osteochondritis dissecans of the medial femoral condyle. The technique involved metal screw fixation of the fragment. Mosaicplasty grafts were then press-fitted through the fragment. Cancellous autograft was utilized in the cases of subchondral bone loss. Patients were followed up clinically and radiologically (Hughston score). Screws were removed arthroscopically at 3 months and the cartilage graded using the International Cartilage Repair Society score. Fragment integration was evaluated by MRI Arthrogram (4 patients).

RESULTS

Median follow-up was 27 months (7-35). Median clinical Hughston score was 2 (0-3) preoperatively and 4 (2-4) postoperatively. Median radiological Hughston score was 3 (2-4) and 4 (3-4). During arthroscopic removal of metalwork, osteochondritis fragments were well integrated in all cases. The International Cartilage Repair Society score was I in one patients, II in five, and III in one. Postoperative MRI arthrograms confirmed that cartilage and bone integration was complete.

CONCLUSIONS

Isolated screw fixation of osteochondritis dissecans in adults provides poor bony integration. Mosaicplasty is an alternative but does not retain normal condylar anatomy. The hybrid fixation technique adds a biological "booster" to osteochondritis fixation, with excellent short-term outcome. Further studies are required to investigate the long-term results.