Meniscectomy leads to early changes in the mineralization distribution of subchondral bone plate

Purpose

It is generally recognized that the subchondral bone plate (SBP) is involved in development of osteoarthritis (OA). However, the pathophysiological significance is not yet clear. The goal of this study is to investigate the extent of the changes that occur in SBP of the tibial plateau in the early stages of experimental OA.

Methods

Forty-three female rabbits were assigned to 5 experimental (n = 8 each group) and one sham group (n = 3). OA was induced by medial meniscectomy in the right knee, the left knee served as control. 2, 4, 8, 12, and 24 weeks after meniscectomy, cartilage damage was evaluated, and bone mineral density (BMD) and mineralization distribution of the SBP was measured by computed tomography osteoabsorptiometry (CT-OAM).

Results

Cartilage damage started 2 weeks after meniscectomy with surface roughening. Cartilage defects increased over time. 24 weeks postoperatively, subchondral bone was exposed. As early as 2 weeks after meniscectomy, BMD in the medial tibial plateau decreased significantly. BMD increased again and reached the values of the non-operated knee 12 weeks postoperatively. In addition, already 4 weeks after meniscectomy a significant shift of the densitiy maximum on the medial tibial plateau, which is normally centrally located toward the margin was observed.

Conclusions

In conclusion, the results of this study contribute to the concept of early involvement of the SBP in the development of OA. The hypothesis that changes in the SBP occur simultaneously to cartilage damage was confirmed.     

Increased cartilage volume after injection of hyaluronic acid in osteoarthritis knee patients who underwent high tibial osteotomy

Purpose

High tibial osteotomy (HTO) is a surgical procedure used to correct abnormal mechanical loading of the knee joint; additionally, intra-articular hyaluronic acid injections have been shown to restore the viscoelastic properties of synovial fluid and balance abnormal biochemical processes. It was hypothesized that combining HTO with intra-articular hyaluronic acid injections would have benefit to improve the cartilage volume of knee joints.

Methods

Forty patients with medial compartment knee osteoarthritis (OA) were randomly placed into 1 of 2 groups. The study group (n = 20) received 2 cycles (at 6-month intervals) of 5 weekly intra-articular hyaluronic acid injections after HTO operation. The control group (n = 20) did not receive any intra-articular injections after HTO surgery. Cartilage volume (primary outcome) was assessed by magnetic resonance imaging (MRI) pre-operatively and 1 year post-operatively. Treatment efficacy (secondary outcomes) was evaluated with the Western Ontario and McMaster Universities OA Index (WOMAC) and by the comparison of the total rescue medication (paracetamol/diclofenac) used (weeks 6, 12, 24, 48).

Results

MRI studies showed a significant increase in total cartilage volume (p = 0.033), lateral femoral cartilage volume (p = 0.044) and lateral tibial cartilage volume (p = 0.027) in the study group. Cartilage volume loss was detected at the lateral tibial plateau in the control group. There were significant improvements after surgery in both groups for all subscales of WOMAC scores (p < 0.001) compared to the baseline. However, no difference was found between the two groups. The study group had significantly lower amounts of diclofenac consumption (p = 0.017).

Conclusion

Based on the findings of the present study, intra-articular hyaluronic acid injections may be beneficial for increasing total cartilage volume and preventing the loss of lateral tibiofemoral joint cartilage after HTO.

Level of evidence

Therapeutic study, Level I.     

The effect of a six-month training program followed by a marathon run on knee joint cartilage volume and thickness in marathon beginners

Purpose

The purpose of this study was to investigate the effect of a 6-month period of intensive running followed by the participation at a marathon run on cartilage volume and thickness in knees of marathon beginners.

Methods

Ten asymptomatic marathon beginners underwent a supervised 6-month training program, which was finalized by the participation at a marathon run. Three-dimensional quantitative magnetic resonance imaging was performed before the training program (baseline measurements) and 1 day after the marathon (follow-up measurements). Cartilage volume and thickness of the medial and lateral femur, medial and lateral tibia, and patella were measured using semiautomated cartilage segmentation and three dimensional data postprocessing.

Results

Significant differences between baseline and follow-up measurements were observed at the lateral femur, where cartilage volume and thickness decreased by a mean of 3.2 ± 3.0 % (p = 0.012) and 1.7 ± 1.6 % (p = 0.010), respectively. No significant changes in cartilage volume and thickness were observed at the medial and lateral tibia, the medial femur, and the patella.

Conclusion

Significant cartilage loss was observed at the lateral femur; however, the measured values are comparable to previously reported precision errors for quantitative cartilage measurement and thus most likely not of clinical relevance. High-impact forces during long-distance running are well tolerated even in marathon beginners and do not lead to clinical relevant cartilage loss.

Level of evidence

IV.     

Influence of age on clinical outcomes of three-dimensional transfer of the tibial tuberosity for patellar instability with patella alta

Purpose

To evaluate the clinical outcomes of three-dimensional (3D) transfer of the tibial tuberosity for patellar instability with patella alta, with a focus on the influence of age at initial surgery.

Methods

Three-dimensional surgery was performed on 28 knees with a mean follow-up of 46 months. Patients were separated into three groups based on the age at initial surgery: group A, 10 knees and an average age of 16.3 ± 1.8 (14–19) years; group B, 10 knees and an average age of 22.1 ± 2.5 (20–28) years; and group C, eight knees and an average age of 44.0 ± 2.2 (40–46) years. Patellofemoral geometry improvement focused on patella alta by determining the Insall–Salvati ratio and Caton–Deschamps index, rotational malalignment by measuring the tibial tubercle–trochlear groove (TT–TG) distance, and lateral patellar subluxation by measuring the patellar tilt. Clinical outcomes were evaluated by the Lysholm and Kujala scores, which were compared before and after surgery. Cartilage degeneration was evaluated by the International Cartilage Repair Society grading system at initial arthroscopy.

Results

The patellar height, TT–TG, and patellar tilt significantly improved in all groups postoperatively (p < 0.05). The Lysholm and Kujala scores also significantly improved postoperatively; however, both scores were lower in group C than in the other groups (p < 0.05). Particularly, pain scores were more severe in group C than in the other groups, and the severity of cartilage degeneration correlated with the pain scores (p < 0.05). Cartilage damage differed significantly between the groups at initial arthroscopy; particularly, group C included grades III and IV cartilage degeneration (p < 0.05).

Conclusions

Age at initial surgery may be the predicting factor for poor clinical outcomes of 3D transfer surgery. The clinical outcome may depend on the age at surgery, which correlated with cartilage damage; thus, surgeons should be given this information when patients are considered undergoing patella surgery.

Level of evidence

Therapeutic case series, Level IV.

     

Cartilage morphology at 2–3 years following anterior cruciate ligament reconstruction with or without concomitant meniscal pathology

Purpose

To examine differences in cartilage morphology between young adults 2–3 years post-anterior cruciate ligament reconstruction (ACLR), with or without meniscal pathology, and control participants.

Methods

Knee MRI was performed on 130 participants aged 18–40 years (62 with isolated ACLR, 38 with combined ACLR and meniscal pathology, and 30 healthy controls). Cartilage defects, cartilage volume and bone marrow lesions (BMLs) were assessed from MRI using validated methods.

Results

Cartilage defects were more prevalent in the isolated ACLR (69 %) and combined group (84 %) than in controls (10 %, P < 0.001). Furthermore, the combined group showed higher prevalence of cartilage defects on medial femoral condyle (OR 4.7, 95 % CI 1.3–16.6) and patella (OR 7.8, 95 % CI 1.5–40.7) than the isolated ACLR group. Cartilage volume was lower in both ACLR groups compared with controls (medial tibia, lateral tibia and patella, P < 0.05), whilst prevalence of BMLs was higher on lateral tibia (P < 0.001), with no significant differences between the two ACLR groups for either measure.

Conclusions

Cartilage morphology was worse in ACLR patients compared with healthy controls. ACLR patients with associated meniscal pathology have a higher prevalence of cartilage defects than ACLR patients without meniscal pathology. The findings suggest that concomitant meniscal pathology may lead to a greater risk of future OA than isolated ACLR.

Level of evidence

III.

     

Cell-free repair of small cartilage defects in the Goettinger minipig: which defect size is possible?

Purpose

Cartilage repair of full-thickness chondral defects in the knees of Goettinger minipigs was assessed by treatment with cell-free collagen type-I gel plugs of three different sizes.

Methods

In 6 adult Goettinger minipigs, three full-thickness chondral defects were created in the trochlear groove of one knee of the hind leg. These defects were treated with a cell-free collagen type-I gel plug of 8, 10, or 12 mm diameter. All animals were allowed unlimited weight bearing. After 1 year, the animals were killed. Immediately after recovery, a non-destructive biomechanical testing was performed. The repair tissue quality was evaluated immunohistologically, collagen type-II protein was quantified, and a semiquantitative score (O’Driscoll score) was calculated.

Results

After 1 year, a high number of cells migrated into the initially cell-free collagen gel plugs and a hyaline-like repair tissue had been created. The O’Driscoll scores were: 8 mm, 21.2 (SD, 2.8); 10 mm, 21.5 (SD, 1.6); and 12 mm, 22.3 (SD, 1.0). The determination of the e-modulus, creep and relaxation revealed that mechanical properties of the two smaller defects were closer to unaffected hyaline cartilage.

Conclusions

As cell-free collagen type-I gel plugs of all three different sizes created hyaline-like repair tissue, this system seems suitable for the treatment of even larger defects.     

Cartilage extra-cellular matrix biomembrane for the enhancement of microfractured defects

Purpose

The purpose of the study was to evaluate whether the biomembrane made of cartilage extracellular matrix, designed to provide cartilage-like favourable environments as well as to prevent against washout of blood clot after microfracture, would enhance cartilage repair compared with the conventional microfracture technique.

Methods

A prospective trial was designed to compare the biomembrane cover after microfracture with conventional microfracture among patients with grade III–IV symptomatic cartilage defect in the knee joint. Patients aged 18–60 years were assigned to either the microfracture/biomembrane (n = 45) or microfracture groups (n = 19). Among them, 24 knees in the microfracture/biomembrane and 12 knees in the microfracture were followed up for 2 years. Cartilage repair was assessed with magnetic resonance imagings taken 6 months, 1 year, and 2 years postoperatively, and the clinical outcomes were also recorded.

Results

Compared with conventional microfracture, microfracture/biomembrane resulted in greater degree of cartilage repair (p = 0.043). In the intra-group analysis, while microfracture showed moderate to good degree of cartilage repair in nearly 50 % of the patients (47 % at 6 months to 50 % at 2 years; n.s.), microfracture/biomembrane maintained an equivalent degree of repair up to 2 years (88 % at 6 months to 75 % at 2 years; n.s.). The clinical outcome at 2 years also showed improved knee score and satisfaction and decreased pain in each group, but the difference between the two groups was not statistically significant.

Conclusions

Compared with conventional microfracture, biomembrane cover after microfracture yielded superior outcome in terms of the degree of cartilage repair during 2 years of follow-up. This implies that initial protection of blood clot and immature repair tissue at the microfractured defect is important for the promotion of enhanced cartilage repair, which may be obtained by the application of a biomembrane.

Level of evidence

Prospective comparative study, Level II.     

The relationship between patellofemoral and tibiofemoral morphology and gait biomechanics following arthroscopic partial medial meniscectomy

Purpose

To examine the relationship between tibiofemoral and patellofemoral joint articular cartilage and subchondral bone in the medial and gait biomechanics following partial medial meniscectomy.

Methods

For this cross-sectional study, 122 patients aged 30–55 years, without evidence of knee osteoarthritis at arthroscopic partial medial meniscectomy, underwent gait analysis and MRI on the operated knee once for each sub-cohort of 3 months, 2 years, or 4 years post-surgery. Cartilage volume, cartilage defects, and bone size were assessed from the MRI using validated methods. The 1st peak in the knee adduction moment, knee adduction moment impulse, 1st peak in the knee flexion moment, knee extension range of motion, and the heel strike transient from the vertical ground reaction force trace were identified from the gait data.

Results

Increased knee stance phase range of motion was associated with decreased patella cartilage volume (B = ?17.9 (95 % CI ?35.4, ?0.4) p = 0.045) while knee adduction moment impulse was associated with increased medial tibial plateau area (B = 7.7 (95 % CI 0.9, 13.3) p = 0.025). A number of other variables approached significance.

Conclusions

Knee joint biomechanics exhibited by persons who had undergone arthroscopic partial meniscectomy gait may go some way to explaining the morphological degeneration observed at the patellofemoral and tibiofemoral compartments of the knee as patients progress from surgery.

Level of evidence

III.     

Autologous chondrocyte implantation in children and adolescents

Purpose

Autologous chondrocyte implantation (ACI) is a well-established treatment method for cartilage defects in knees. Age-related grouping was based on expression data of cartilage-specific markers. Specificities of ACI in the different populations were analysed.

Methods

Two hundred and sixty-seven patients undergoing ACI in the knee between 2006 and 2010 were included in this analysis. Cell characteristics and expression data of cartilage-specific surface markers as CD44, aggrecan and collagen type II were statistically analysed for age association. Epidemiological data of the defined groups were compared. Course of treatment was evaluated using MRI.

Results

A correlation analysis showed statistically significant associations between age and aggrecan or collagen type II expression in all patients <30 years. A cluster analysis could predict age-dependent expression of these markers separating groups with an average age of 18.1 ± 2.3 and 23.6 ± 4.2 years, respectively (p < 0.02). Discriminance analysis suggested the age border between adults and juveniles at about 20 years. There was no influence of age on cell characteristics or CD44 expression. In the 19 of 267 patients with an age ≤18 years, gender distribution was not different compared to adults, but patella was significantly more affected. Cartilage lesions were mainly caused by osteochondritis dissecans (OCD) and trauma. The Knee Osteoarthritis Scoring System in MRI reached 4.8 ± 2.3 points before, declining to 3.3 ± 2.3 points 6 and 12 months after the operation.

Conclusions

Age-related expression of cartilage-specific markers allows definition of adolescents in cartilage regenerating surgery. Chondromalacia in these patients is mainly caused by OCD or trauma.

Level of evidence

Case series, Level IV.     

Prevalence of cartilage lesions and early osteoarthritis in patients with patellar dislocation

Objectives

Assessment of cartilage lesions and osteoarthritis (OA) of the patellofemoral joint in patients following lateral patellar dislocation using magnetic resonance imaging (MRI).

Methods

MR images of 129 knees (mean age 26?years, range 11–56) grouped as acute (A), recurrent (B), and chronic (C) dislocators were analysed regarding the prevalence and severity of patellofemoral cartilage lesions. Grades of OA were assessed using modified WORMS.

Results

In groups A, B, and C the prevalence of cartilage lesions was 71%, 82%, and 97%, respectively. Most lesions were located on the central patella in groups A and B (central 69% and 78%; medial 56% and 47%; lateral 31% and 42%), whereas group C revealed all regions affected (73%, 61%, and 67%). Of group A, 14% had mild OA and 64% of group B. Group C showed mild OA in 62% and moderate OA in 18%. Cartilage defect size and prevalence of OA was correlated with number of dislocations (r?=?0.41 and r?=?0.59; P?<?0.001).

Conclusions

Cartilage lesions and early OA are common after patellar dislocation and appear to increase with the frequency of dislocation. Both conditions should be considered when interpreting MRI in such patients, because of implications for treatment.

Key Points

? Cartilage lesions are very common after patellar dislocation. ? The severity of cartilage lesions increases with number of dislocations. ? Osteoarthritis is common after recurrent patellar dislocation, even in young patients. ? Detecting cartilage lesions is important after patellar dislocation.     

Osteoarthritis of the patella, lateral femoral condyle and posterior medial femoral condyle correlate with range of motion

Purpose

The type of osteoarthritis and the degree of severity which causes restriction of knee range of motion (ROM) is still largely unknown. The objective of this study was to analyse the location and the degree of cartilage degeneration that affect knee range of motion and the connection, if any, between femorotibial angle (FTA) and knee ROM restriction.

Methods

Four hundreds and fifty-six knees in 230 subjects with knee osteoarthritis undergoing knee arthroplasty were included. Articular surface was divided into eight sections, and cartilage degeneration was evaluated macroscopically during the operation. Cartilage degeneration was classified into four grades based on the degree of exposure of subchondral bone. A Pearson correlation was conducted between FTA and knee flexion angle to determine whether high a degree of FTA caused knee flexion restriction. A logistic regression analysis was also conducted to detect the locations and levels of cartilage degeneration causing knee flexion restriction.

Results

No correlation was found between FTA and flexion angle (r = ?0.08). Flexion angle was not restricted with increasing FTA. Logistic regression analysis showed significant correlation between restricted knee ROM and levels of knee cartilage degeneration in the patella (odds ratio (OR) = 1.77; P = 0.01), the lateral femoral condyle (OR = 1.62; P = 0.03) and the posterior medial femoral condyle (OR = 1.80; P = 0.03).

Conclusion

For clinical relevance, soft tissue release and osteophyte resection around the patella, lateral femoral condyle and posterior medial femoral condyle might be indicated to obtain a higher degree of knee flexion angle.

Level of evidence

Case–control study, Level III.     

Effect of autologous platelet-rich plasma on the repair of full-thickness articular defects in rabbits

Purpose

To assess the effect of autologous platelet-rich plasma on the repair of full-thickness articular cartilage lesions in immature rabbits. To that end, the samples were studied using macroscopic, microscopic and biomechanical techniques.

Methods

Twenty-four 11-week-old New Zealand rabbits were divided into two groups based on the treatment (physiological saline serum PCB, autologous platelet-rich plasma PRP). Cartilage lesions were drilled in medial femoral condyle of these rabbits. Other 12 rabbits were under the same conditions, but they did not suffer any lesion and treatment (control group CTR). The three groups were divided into two subgroups, depending on the age at the time of killing (16 and 19 weeks old).

Results

The CTR group showed the best possible value in the macroscopic and microscopic evaluation. Meanwhile, the PCB and PRP group values were lower than the CTR group values, at two times of the study, but similar to each other at 19 weeks. In the biomechanical study, at 16 weeks, the CTR and PCB groups behaved similarly, with values above PRP group values, while at 19 weeks, CTR group showed higher values than PCB and PRP groups, and there were no differences between these values.

Conclusions

The evolution of the tissue treated with autologous PRP showed a positive tendency over time, while the PCB group was negative. Nevertheless, at 19 weeks of age, the PRP treatment did not show better results than the PCB, both showing the characteristics of fibrocartilaginous tissue. Likewise, none of the two treatments produced a repair tissue as the healthy cartilage.     

Xenotransplantation of human mesenchymal stem cells for repair of osteochondral defects in rabbits using osteochondral biphasic composite constructs

Purpose

The aim of this work is to investigate the feasibility of non-autologous transplantation of human mesenchymal stem cells (hMSCs) with or without differentiation for the regeneration of osteochondral defects in rabbits using a biphasic composite construct composed of platelet-rich fibrin glue (PR-FG) and hydroxyapatite.

Methods

After isolation and culture, hMSCs were seeded on biphasic composite constructs (hydroxyapatite + PR-FG) and transplanted into osteochondral defects of adult New Zealand white rabbits. Treatment of individual defects was applied by random assignment to one of five groups: (1) control, defects untreated; (2) hydroxyapatite, defects filled with hydroxyapatite only; (3) hydroxyapatite + PR-FG, defects filled with a composite of hydroxyapatite and PR-FG; (4) hydroxyapatite + PR-FG + undifferentiated hMSCs; and (5) hydroxyapatite + PR-FG + differentiated hMSCs. Rabbits were killed at 4 or 8 weeks post-surgery, at which time osteochondral repair was macroscopically and histologically evaluated and scored using the modified International Cartilage Repair Society scoring system.

Results

The group in which defects were seeded with differentiated hMSCs (group 5) showed superior healing of osteochondral defects based on macroscopic and histological observations compared to other groups. Specifically, 8 weeks after implantation, defects were filled with more hyaline-like cartilage and were better integrated with the surrounding native cartilage. The histological scores were significantly better than those of other groups (16.3 at 8 weeks, p < 0.01).

Conclusion

Xenogeneic transplantation of differentiated hMSCs using a biphasic composite construct effectively repaired osteochondral defect in a rabbit model. Differentiated hMSCs showed superior healing of chondral lesion to undifferentiated hMSCs.     

Exploring cartilage damage in gout using 3-T MRI: distribution and associations with joint inflammation and tophus deposition

Objective

Few imaging studies have investigated cartilage in gout. Magnetic resonance imaging (MRI) can image cartilage damage and also reveals other features of gouty arthropathy. The objective was to develop and validate a system for quantifying cartilage damage in gout.

Methods

3-T MRI scans of the wrist were obtained in 40 gout patients. MRI cartilage damage was quantified using an adaptation of the radiographic Sharp van der Heijde score. Two readers scored cartilage loss at 7 wrist joints: 0 (normal), 1 (partial narrowing), 2 (complete narrowing) and concomitant osteoarthritis was recorded. Bone erosion, bone oedema and synovitis were scored (RAMRIS) and tophi were assessed. Correlations between radiographic and MRI cartilage scores were investigated, as was the reliability of the MRI cartilage score and its associations.

Results

The GOut MRI Cartilage Score (GOMRICS) was highly correlated with the total Sharp van der Heijde (SvdH) score and the joint space narrowing component (R?=?0.8 and 0.71 respectively, p?<?0.001). Reliability was high (intraobserver, interobserver ICCs?=?0.87 [0.57–0.97], 0.64 [0.41–0.79] respectively), and improved on unenhanced scans; interobserver ICC?=?0.82 [0.49–0.95]. Cartilage damage was predominantly focal (82 % of lesions) and identified in 40 out of 280 (14 %) of joints. Cartilage scores correlated with bone erosion (R?=?0.57), tophus size (R?=?0.52), and synovitis (R?=?0.55), but not bone oedema scores.

Conclusions

Magnetic resonance imaging can be used to investigate cartilage in gout. Cartilage damage was relatively uncommon, focal, and associated with bone erosions, tophi and synovitis, but not bone oedema. This emphasises the unique pathophysiology of gout.     

Satisfactory long-term MRI after autologous chondrocyte implantation at the knee

Purpose

Autologous chondrocyte implantation (ACI) to address isolated condylar lesions is supposed to limit degenerative deterioration in neutrally aligned knees. Here, we report long-term results of the first-generation ACI technique with periosteal flap.

Methods

Twelve patients, 29 years old on average, were included on the basis of pre-operative MRI selection of lesions >2 cm². Cartilage carrots were harvested arthroscopically, then cultured and finally re-implanted within a mean time interval of 12 weeks. Ten-year MRI results were analysed according to a semi-quantitative scale, along with functional assessment based on International Knee Documentation Committee score, Lysholm et al. score and the Tegner et al. activity scale.

Results

One patient secondarily required valgus tibial osteotomy with mosaic plasty. Another incurred graft hypertrophy that necessitated arthroscopic peeling. MRI showed that cartilage repair filled more than 50 % of the initial defect in 9 patients. Standard radiographs revealed slight narrowing of the joint line. Overall, functional scores improved durably by 50 %, although activity level decreased substantially.

Conclusion

ACI contained degenerative changes within moderate stages while maintaining durable functional improvement. However, in the absence of controls, it was difficult to differentiate between these findings and the spontaneous evolution of non-treated lesions.

Level of evidence

Case series, Level IV.     

T2 values of articular cartilage in clinically relevant subregions of the asymptomatic knee

Purpose

In order for T2 mapping to become more clinically applicable, reproducible subregions and standardized T2 parameters must be defined. This study sought to: (1) define clinically relevant subregions of knee cartilage using bone landmarks identifiable on both MR images and during arthroscopy and (2) determine healthy T2 values and T2 texture parameters within these subregions.

Methods

Twenty-five asymptomatic volunteers (age 18–35) were evaluated with a sagittal T2 mapping sequence. Manual segmentation was performed by three raters, and cartilage was divided into twenty-one subregions modified from the International Cartilage Repair Society Articular Cartilage Mapping System. Mean T2 values and texture parameters (entropy, variance, contrast, homogeneity) were recorded for each subregion, and inter-rater and intra-rater reliability was assessed.

Results

The central regions of the condyles had significantly higher T2 values than the posterior regions (P < 0.05) and higher variance than the posterior region on the medial side (P < 0.001). The central trochlea had significantly greater T2 values than the anterior and posterior condyles. The central lateral plateau had lower T2 values, lower variance, higher homogeneity, and lower contrast than nearly all subregions in the tibia. The central patellar regions had higher entropy than the superior and inferior regions (each P ≤ 0.001). Repeatability was good to excellent for all subregions.

Conclusion

Significant differences in mean T2 values and texture parameters were found between subregions in this carefully selected asymptomatic population, which suggest that there is normal variation of T2 values within the knee joint. The clinically relevant subregions were found to be robust as demonstrated by the overall high repeatability.     

Cartilage repair using mesenchymal stem cell (MSC) sheet and MSCs-loaded bilayer PLGA scaffold in a rabbit model

Purpose

The integration of regenerated cartilage with surrounding native cartilage is a major challenge for the success of cartilage tissue-engineering strategies. The purpose of this study is to investigate whether incorporation of the power of mesenchymal stem cell (MSC) sheet to MSCs-loaded bilayer poly-(lactic-co-glycolic acid) (PLGA) scaffolds can improve the integration and repair of cartilage defects in a rabbit model.

Methods

Rabbit bone marrow-derived MSCs were cultured and formed cell sheet. Full-thickness cylindrical osteochondral defects (4 mm in diameter, 3 mm in depth) were created in the patellar groove of 18 New Zealand white rabbits and the osteochondral defects were treated with PLGA scaffold (n = 6), PLGA/MSCs (n = 6) or MSC sheet-encapsulated PLGA/MSCs (n = 6). After 6 and 12 weeks, the integration and tissue response were evaluated histologically.

Results

The MSC sheet-encapsulated PLGA/MCSs group showed significantly more amounts of hyaline cartilage and higher histological scores than PLGA/MSCs group and PLGA group (P < 0.05). In addition, the MSC sheet-encapsulated PLGA/MCSs group showed the best integration between the repaired cartilage and surrounding normal cartilage and subchondral bone compared to other two groups.

Conclusions

The novel method of incorporation of MSC sheet to PLGA/MCSs could enhance the ability of cartilage regeneration and integration between repair cartilage and the surrounding cartilage. Transplantation of autologous MSC sheet combined with traditional strategies or cartilage debris might provide therapeutic opportunities for improving cartilage regeneration and integration in humans.     

Three-dimensional topographical variation of femoral cartilage T2 in healthy volunteer knees

Objective

Quantitative knee cartilage T2 assessment on limited two-dimensional midsagittal or midcoronal planes may be insufficient to assess variations in normal cartilage composition. The purpose of this work was to reveal characteristic 3D distribution of T2 values in femoral cartilage in healthy volunteer knees.

Materials and methods

Sixteen volunteers were enrolled in this study. One knee joint in each volunteer was imaged using a 3D fast image employing steady-state acquisition cycled phases (FIESTA-C) sequence for modeling distal femoral morphology, as well as a sagittal T2 mapping of cartilage. 3D distribution of cartilage T2 values was generated for the femoral condyles. At each medial and lateral condyle, four regions of interest (ROI) were manually defined based on the cartilage covered by the 3D surface model of the medial and lateral menisci.

Results

The 3D maps showed a relatively inhomogeneous distribution of cartilage T2 on the medial and lateral condyles. Cartilage T2 values in the internal half of the weight-bearing zone were significantly higher than those in all other zones on both lateral and medial condyles.

Conclusions

Analysis of 3D distribution of femoral cartilage T2 may be valuable in determining the site-specific normal range of cartilage T2 in the healthy knee joint.     

Feasibility of in vivo diffusion tensor imaging of articular cartilage with coverage of all cartilage regions

Objectives

To investigate the value of diffusion tensor imaging (DTI) of articular cartilage to differentiate healthy from osteoarthritis (OA) subjects in all cartilage regions.

Methods

DTI was acquired sagittally at 7 T in ten healthy and five OA (Kellgren-Lawrence grade 2) subjects with a line scan diffusion tensor sequence (LSDTI). Three healthy volunteers and two OA subjects were examined twice to assess the test-retest reproducibility. Averaged mean diffusivity (MD) and fractional anisotropy (FA) were calculated in each cartilage region (femoral trochlea, lateral and medial femoral condyles, patella, and lateral and medial tibia).

Results

The test-retest reproducibility was 2.9 % for MD and 5.6 % for FA. Averaged MD was significantly increased (+20 %, p?<?0.05) in the OA subjects in the lateral femoral condyle, lateral tibia and the femoral trochlea compartments. Averaged FA presented a trend of lower values in the OA subjects (-12 %), which was only significant for the lateral tibia.

Conclusions

In vivo DTI of articular cartilage with coverage of all cartilage regions using an LSDTI sequence is feasible, shows excellent reproducibility for MD and FA, and holds potential for the diagnosis of OA.

Key points

? DTI of articular cartilage is feasible at 7 T in all cartilage regions ? DTI of articular cartilage can potentially differentiate healthy and OA subjects     

Quantitative magnetic resonance imaging (MRI) morphological analysis of knee cartilage in healthy and anterior cruciate ligament-injured knees

Purpose

To analyze the morphological change in the cartilage of the knee after anterior cruciate ligament (ACL) injury by comparing with that of the intact contralateral knee.

Methods

A total of 22 participants (12 male and 10 female patients) who had unilateral ACL injury underwent MRI scan of both the injured and intact contralateral knees. Sagittal plane images were segmented using a modeling software to determine cartilage volume and cartilage thickness in each part of the knee cartilage that were compared between the ACL-injured and the intact contralateral knees. Furthermore, the male and female patients’ data were analyzed in subgroups.

Results

The ACL-injured knees had statistically significant lower total knee cartilage volume than the intact contralateral knees (P = 0.0020), but had similar mean thickness of total knee cartilage (not significant: n.s.). In the male subgroup, there was no significant difference in cartilage volume and thickness between normal and ACL-injured knees. In the female subgroup, the ACL-injured knees demonstrated statistically significant difference in total knee cartilage volume (P = 0.0004) and thickness (P = 0.0024) compared with the normal knees. The percentage change in the cartilage thickness in women was significantly greater than that in men.

Conclusion

Cartilage volume was significantly smaller in the ACL-injured knees than in the contralateral intact knees in this cohort. Women tended to display greater cartilage volume and thickness change after ACL injury than men. These findings indicated that women might be more susceptible to cartilage alteration after ACL injuries.

Level of evidence

III.