Microfracture: Its History and Experience of the Developing Surgeon

The Statistical Fragility of Marrow Stimulation for Cartilage Defects of the Knee: A Systematic Review of Randomized Controlled Trials

OBJECTIVE

Marrow stimulation is used to address knee cartilage defects. In this study, we used the fragility index (FI), reverse fragility index (rFI), and fragility quotient (FQ) to evaluate statistical fragility of outcomes reported in randomized controlled trials (RCTs) evaluating marrow stimulation.

DESIGN

PubMed, Embase, and MEDLINE were queried for recent RCTs (January 1, 2010-September 5, 2023) assessing marrow stimulation for cartilage defects of the knee. The FI and rFI were calculated as the number of outcome event reversals required to alter statistical significance for significant and nonsignificant outcomes, respectively. The FQ was determined by dividing the FI by the study sample size.

RESULTS

Across 155 total outcomes from 21 RCTs, the median FI was 3 (interquartile range [IQR], 2-5), with an associated median FQ of 0.067 (IQR, 0.033-0.010). Thirty-two outcomes were statistically significant, with a median FI of 2 (IQR, 1-3.25) and FQ of 0.050 (IQR, 0.025-0.069). Ten of the 32 (31.3%) outcomes reported as statistically significant had an FI of 1. In total, 123 outcomes were nonsignificant, with a median rFI of 3 (IQR, 2-5). Studies assessing stem cell augments were the most fragile, with a median FI of 2. In 55.5% of outcomes, the number of patients lost to follow-up was greater than or equal to the FI.

CONCLUSION

Statistical findings in RCTs evaluating marrow stimulation for cartilage defects of the knee are statistically fragile. We recommend combined reporting of P-values with FI and FQ metrics to aid in the interpretation of clinical findings in comparative trials assessing cartilage restoration.

Drop in survivorship 13 years after AMIC procedures in aligned knees: A long-term follow-up

PURPOSE

Autologous matrix-induced chondrogenesis (AMIC) showed promising short-term results comparable to microfracture. This study aims to assess the 19-year outcomes of AMIC, addressing the lack of long-term data.

METHODS

Retrospective cohort of 34 knees treated with AMIC underwent a 19-year follow-up. The primary outcome was AMIC survival, considering total knee arthroplasty as a failure event. Survival analysis for factors that were associated with longer survival of the AMIC was also performed. Clinical and radiological outcome scores were analysed for the AMIC group.

RESULTS

Twenty-three knees were available for follow-up analysis. Of these, 14 (61%) underwent revision surgery for total knee arthroplasty (TKA). The mean time was 13.3 ± 2.5 years (range: 9-17 years). Secondary outcomes showed that increased age at surgery (hazard ratio [HR]: 1.05; p = 0.021) and larger defect size (HR: 1.95; p = 0.018) were risk factors for failure. Concomitant proximal tibial osteotomy (HR: 0.22; p = 0.019) was associated with longer survival. The remaining nine knees (39%) were analysed as a single group. The mean clinical score at follow-up of 18.6 ± 0.9 SD years was 79.5 ± 19.7 SD for the Lysholm score, 1.8 ± 1.5 SD for the visual analog scale score, 74.2 ± 22.4 SD for the KOOS score and a median of 3 (range: 3-4) for the Tegner activity scale.

CONCLUSIONS

The mean survival time of 13.3 years indicates the durability of AMIC in properly aligned knees. Nonetheless, despite a 61% conversion to TKA, the knees that persisted until the 19-year follow-up remained stable, underscoring the procedure's longevity and consistent clinical outcomes.

LEVEL OF EVIDENCE

Level IV.

Enhancing Cartilage Repair: Surgical Approaches, Orthobiologics, and the Promise of Exosomes

Treating cartilage damage is challenging as its ability for self-regeneration is limited. Left untreated, it can progress to osteoarthritis (OA), a joint disorder characterized by the deterioration of articular cartilage and other joint tissues. Surgical options, such as microfracture and cell/tissue transplantation, have shown promise as techniques to harness the body's endogenous regenerative capabilities to promote cartilage repair. Nonetheless, these techniques have been scrutinized due to reported inconsistencies in long-term outcomes and the tendency for the defects to regenerate as fibrocartilage instead of the smooth hyaline cartilage native to joint surfaces. Orthobiologics are medical therapies that utilize biologically derived substances to augment musculoskeletal healing. These treatments are rising in popularity because of their potential to enhance surgical standards of care. More recent developments in orthobiologics have focused on the role of exosomes in articular cartilage repair. Exosomes are nano-sized extracellular vesicles containing cargo such as proteins, lipids, and nucleic acids, and are known to facilitate intercellular communication, though their regenerative potential still needs to be fully understood. This review aims to demonstrate the advancements in cartilage regeneration, highlight surgical and biological treatment options, and discuss the recent strides in understanding the precise mechanisms of action involved.

Save the subchondral bone plate: Debridement versus bone marrow stimulation in acetabular cartilage defects over 60 months of follow-up

PURPOSE

Bone marrow stimulation is a common treatment for full-thickness cartilage defects in the hip joint. However, common procedures may result in poor fibrous repair tissue and changes to the subchondral anatomy. This study investigated the clinical outcome of a cohort of International Cartilage Repair Society (ICRS) grades 3 and 4 cartilage defects treated with bone marrow stimulation compared to those who received simple debridement/chondroplasty.

METHODS

In this retrospective registry study, 236 patients with uni-focal acetabular chondral lesions of the hip up to 400 mm² (mean 177.4 ± 113.4 mm²) and of ICRS grade ≥3 with follow-up of at least 12 months (mean 33.2 ± 15.3 months) were included. Eighty-one patients underwent bone marrow stimulation (microfracture: n = 44, abrasion: n = 37) besides treatment of the underlying pathology, 155 patients underwent defect debridement/chondroplasty. The patient-reported outcome was measured using the International Hip Outcome Tool 33 (iHOT33) score and the Visual Analogue Scale (VAS) for pain.

RESULTS

iHOT33 and VAS both improved highly statistically significantly (p < 0.001) in the debridement group after 6, 12, 24, 36 and 60 months compared to the preoperative scores, whereas iHOT33 and VAS after microfracture or abrasion did not show statistically significant changes over time. Twenty-four and sixty months postsurgery the debridement group revealed significant higher scores in the iHOT33 compared to the bone marrow stimulation groups.

CONCLUSION

Patients with chondral lesions of the hip ≤400 mm2 sustainably benefit from arthroscopic debridement under preservation of the subchondral bone plate in terms of functional outcome and pain in contrast to patients treated with bone marrow stimulation. These findings discourage the currently recommended use of microfracture in the hip joint.

LEVEL OF EVIDENCE

Level III.

Cartilage Integrity: A Review of Mechanical and Frictional Properties and Repair Approaches in Osteoarthritis

Osteoarthritis (OA) is one of the most common causes of disability around the globe, especially in aging populations. The main symptoms of OA are pain and loss of motion and function of the affected joint. Hyaline cartilage has limited ability for regeneration due to its avascularity, lack of nerve endings, and very slow metabolism. Total joint replacement (TJR) has to date been used as the treatment of end-stage disease. Various joint-sparing alternatives, including conservative and surgical treatment, have been proposed in the literature; however, no treatment to date has been fully successful in restoring hyaline cartilage. The mechanical and frictional properties of the cartilage are of paramount importance in terms of cartilage resistance to continuous loading. OA causes numerous changes in the macro- and microstructure of cartilage, affecting its mechanical properties. Increased friction and reduced load-bearing capability of the cartilage accelerate further degradation of tissue by exerting increased loads on the healthy surrounding tissues. Cartilage repair techniques aim to restore function and reduce pain in the affected joint. Numerous studies have investigated the biological aspects of OA progression and cartilage repair techniques. However, the mechanical properties of cartilage repair techniques are of vital importance and must be addressed too. This review, therefore, addresses the mechanical and frictional properties of articular cartilage and its changes during OA, and it summarizes the mechanical outcomes of cartilage repair techniques.

[Advances in clinical repair techniques for localized knee cartilage lesions]

Objective

To summarize the classic and latest treatment techniques for localized knee cartilage lesions in clinical practice and create a new comprehensive clinical decision-making process.

Methods

The advantages and limitations of various treatment methods for localized knee cartilage lesions were summarized by extensive review of relevant literature at home and abroad in recent years.

Results

Currently, there are various surgical methods for treating localized knee cartilage injuries in clinical practice, each with its own pros and cons. For patients with cartilage injuries less than 2 cm 2 and 2-4 cm 2 with bone loss are recommended to undergo osteochondral autograft (OAT) and osteochondral allograft (OCA) surgeries. For patients with cartilage injuries less than 2 cm 2 and 2-4 cm 2 without bone loss had treatment options including bone marrow-based techniques (micro-fracture and ogous matrix induced chondrogenesis), autologous chondrocyte implantation (ACI)/matrix-induced ACI, particulated juvenile allograft cartilage (PJAC), OAT, and OCA. For patients with cartilage injuries larger than 4 cm 2 with bone loss were recommended to undergo OCA. For patients with cartilage injuries larger than 4 cm 2 without bone loss, treatment options included ACI/matrix-induced ACI, OAT, and PJAC.

Conclusion

There are many treatment techniques available for localized knee cartilage lesions. Treatment strategy selection should be based on the size and location of the lesion, the extent of involvement of the subchondral bone, and the level of evidence supporting each technique in the literature.

Regeneration: Bone-Marrow Stimulation of the Talus-Limits and Goals

Bone Marrow Stimulation of osteochondral lesions of the talus has been shown to be a successful way to treat cartilage injuries. Newer data suggest that Bone Marrow Stimulation is best reserved for osteochondral lesions of the talus Sizes Less Than 107.4 mm2 in area. Additionally, newer smaller and deeper techniques to perform bone marrow stimulation have resulted in less subchondral bone damage, less cancellous compaction, and superior bone marrow access with multiple trabecular access channels. Biologic adjuvants such as platelet-rich plasma (PRP), hyaluronic acid (HA), and bone marrow aspirate concentrate (BMAC) may lead to better functional outcomes when used concomitant to bone marrow stimulation.

A comprehensive review of hip arthroscopy techniques and outcomes

Transforming the orthopedic landscape, hip arthroscopy pioneers a minimally invasive surgical approach for diagnosing and addressing hip pathologies. With its origins dating back to Burman's 1931 cadaveric study, this groundbreaking technique gained clinical relevance in 1939 through Takagi's report. However, the 1980s marked the actual emergence of hip arthroscopy for treating a wide range of hip disorders. Now, a staple in modern orthopedics, hip arthroscopy empowers patients with previously undiagnosed and untreated hip conditions, enabling them to obtain relief and reclaim their lives. By employing a compact camera and specialized tools, surgeons expertly navigate the hip joint, performing procedures from excising loose bodies and mending labral tears to addressing femoroacetabular impingement and tackling other intricate issues. This innovative approach has dramatically elevated patients' quality of life, allowing them to embrace targeted treatments and resume daily activities without resorting to lifestyle alterations.

Pediatric Knee Injury: A Unique Case of Intra-articular Osteochondral Fracture Following Penetrating Trauma

Penetrating injuries to the musculoskeletal system pose common challenges for orthopedic surgeons in emergency departments (EDs). The complexity escalates when a joint is affected, increasing the risk of severe complications such as infection and post-traumatic arthritis. Given the potential importance of these injuries, early diagnosis and a meticulous treatment plan are crucial. In this paper, we present a unique case of penetrating trauma, resulting in an intra-articular defect on the lateral femoral condyle of an adolescent girl. This case underscores the importance of tailored interventions in managing complex musculoskeletal injuries.

Decellularized allogeneic cartilage paste with human costal cartilage and crosslinked hyaluronic acid-carboxymethyl cellulose carrier augments microfracture for improved articular cartilage repair

Articular cartilage lacks natural healing abilities and necessitates surgical treatments for injuries. While microfracture (MF) is a primary surgical approach, it often results in the formation of unstable fibrocartilage. Delivering hyaline cartilage directly to defects poses challenges due to the limited availability of autologous cartilage and difficulties associated with allogeneic cartilage delivery. We developed a decellularized allogeneic cartilage paste (DACP) using human costal cartilage mixed with a crosslinked hyaluronic acid (HA)-carboxymethyl cellulose (CMC) carrier. The decellularized allogeneic cartilage preserved the extracellular matrix and the nanostructure of native hyaline cartilage. The crosslinked HA-CMC carrier provided shape retention and moldability. In vitro studies confirmed that DACP did not cause cytotoxicity and promoted migration, proliferation, and chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells. After 6 months of implantation in rabbit knee osteochondral defects, DACP combined with MF outperformed MF alone, demonstrating improved gait performance, defect filling, morphology, extracellular matrix deposition, and biomechanical properties similar to native cartilage. Thus, DACP offers a safe and effective method for articular cartilage repair, representing a promising augmentation to MF. STATEMENT OF SIGNIFICANCE: Directly delivering hyaline cartilage to repair articular cartilage defects is an ideal treatment. However, current allogeneic cartilage products face delivery challenges. In this study, we developed a decellularized allogeneic cartilage paste (DACP) by mixing human costal cartilage with crosslinked hyaluronic acid (HA)-carboxymethyl cellulose (CMC). DACP preserves extracellular matrix components and nanostructures similar to native cartilage, with HA-CMC ensuring shape retention and moldability. Our study demonstrates improved cartilage repair by combining DACP with microfracture, compared to microfracture alone, in rabbit knee defects over 6 months. This is the first report showing better articular cartilage repair using decellularized allogeneic cartilage with microfracture, without the need for exogenous cells or bioactive substances.

Long-term clinical and radiological outcomes following arthroscopic microfracture of the glenohumeral joint for chondral defects

Background

The primary aim of this study was to evaluate mid- and long-term outcomes following microfracture in patients with glenohumeral chondral lesions.

Methods

This prospective cohort study assessed patients with shoulder pain who were treated with arthroscopic microfracture for full-thickness chondral lesions of the glenohumeral joint. Outcomes included the Simple Shoulder Test at baseline, mid-term (approximately 1 year) and long-term (approximately 10 years), and the Oxford Shoulder Score, shoulder pain (0-10 numerical scale) and radiological assessment using a modified Samilson & Prieto score at long-term follow-up. Data were analyzed with paired t-tests and Wilcoxon's signed rank tests, which were considered significant if P < .05.

Results

Twenty-five patients with a mean age of 52.7 ± 12.1 were enrolled. The mean Simple Shoulder Test score improved from baseline to 1 year (6.7 ± 2.5 to 11.0 ± 1.4, P < .001), which was maintained at long-term follow-up (10.3 ± 2.1, P < .001). Additionally, at long-term follow-up, Oxford Shoulder Score and Verbal Pain Score scores were 43 ± 4.8 and 1.1 ± 1.5, respectively while median modified Samilson & Prieto scores increased from 1 preoperatively to 2 at 10 years (P < .001).

Conclusion

Patients undergoing microfracture for full-thickness chondral lesions of the glenohumeral joint reported substantial improvements in shoulder pain and function at 1 and 10 years, despite progressive radiological degeneration.

Treatment of Chondral Lesions in the Knee

Articular cartilage injuries are common and lead to early joint deterioration and osteoarthritis. Articular cartilage repair techniques aim at forming a cartilaginous neo-tissue to support the articular load and prevent progressive degeneration. Several techniques are available for this purpose, such as microfracture and chondrocyte transplantation. However, the procedural outcome is often fibrocartilage, which does not have the same mechanical resistance as cartilaginous tissue. Procedures with autologous osteochondral graft have a morbidity risk, and tissue availability limits their use. As such, larger lesions undergo osteochondral transplantation using fresh or frozen grafts. New techniques using minced or particulate cartilage fragments or mesenchymal stem cells are promising. This paper aims to update the procedures for treating chondral lesions of the knee.

Autologous blood clots: a natural biomaterial for wound healing

Repair after injury in mammalian tissue involves a complex cascade of events, with the formation of local blood clots being essential for the initial phases of wound healing. As a result, emerging research has sought to harness this biological activity to generate a pro-regenerative biomaterial to speed up wound healing. According to recent studies, “blood clots” created in vitro can be employed as an orthobiologic-based biomaterial for promoting tissue regeneration. Even though such research is still in its early phases, numerous studies show encouraging results that suggest autologous blood clots created in vitro might be a valuable treatment for soft tissue and orthopedic injuries. In this article, we discuss the function of blood clots in physiologic healing, how exogenous material can affect this process, and the most recent clinical research that proposes the use of autologous blood clots as a therapeutically beneficial biomaterial.

Particulated Costal Allocartilage With Microfracture Versus Microfracture Alone for Knee Cartilage Defects: A Multicenter, Prospective, Randomized, Participant- and Rater-Blinded Study

Background

Microfracture is the first-line treatment for cartilage defects; however, the suboptimal quality of the repaired cartilage remains an issue.

Purpose/Hypothesis

The aim of this first in-human study was to compare the clinical efficacy and safety of a combination of particulated costal allocartilage and microfracture versus microfracture alone in treating knee cartilage defects. We hypothesized that the particulated costal allocartilage with microfracture would result in superior cartilage repair quality and better clinical outcomes at 48 weeks postoperatively.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

Patients with cartilage defects were allocated randomly to the treatment group (particulated costal allocartilage with microfracture) and control group (microfracture alone). Magnetic resonance imaging (MRI) outcomes of cartilage repair (the primary outcome measure) were evaluated at the 48-week follow-up using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Patient-reported clinical outcomes (visual analog scale [VAS] pain score, Knee injury and Osteoarthritis Outcome Score [KOOS], and International Knee Documentation Committee score) and adverse events were evaluated at 12, 24, and 48 weeks postoperatively.

Results

Overall, 88 patients were included (44 patients each in the treatment and control groups). The total MOCART score at 48 weeks postoperatively was significantly higher in the treatment group than in the control group (P < .001). Among the 9 MOCART variables, 6 were significantly superior in the treatment versus the control group: degree of repair and defect filling (P < .001), integration to the border zone (P < .001), surface (P = .006), structure (P = .011), signal intensity of the repair tissue (P < .001), and subchondral lamina (P = .005). There were significant between-group differences in KOOS-Pain (P = .014), KOOS-Activities of Daily Living (P = .010), KOOS-Sports (P = .029), and KOOS-Symptoms (P = .039) at 12 weeks postoperatively and in VAS pain (P = .012) and KOOS-Pain (P = .005) at 24 weeks postoperatively. At 48 weeks postoperatively, clinical outcomes were comparable between the groups.

Conclusion

Microfracture augmented with particulated costal allocartilage resulted in superior cartilage repair quality compared with microfracture alone in terms of MRI evaluation of the knee joint cartilage defect at the 48-week follow-up. Functional outcomes were favorable for both treatments at final follow-up.

Registration

KCT0004936 (Clinical Research Information Service [CRiS] of the Republic of Korea).

Current and Novel Therapeutics for Articular Cartilage Repair and Regeneration

Articular cartilage repair is a sophisticated process that has is being recently investigated. There are several different approaches that are currently reported to promote cartilage repair, like cell-based therapies, biologics, and physical therapy. Cell-based therapies involve the using stem cells or chondrocytes, which make up cartilage, to promote the growth of new cartilage. Biologics, like growth factors, are also being applied to enhance cartilage repair. Physical therapy, like exercise and weight-bearing activities, can also be used to promote cartilage repair by inducing new cartilage growth and improving joint function. Additionally, surgical options like osteochondral autograft, autologous chondrocyte implantation, microfracture, and others are also reported for cartilage regeneration. In the current literature review, we aim to provide an up-to-date discussion about these approaches and discuss the current research status.

The effects of losartan or angiotensin II receptor antagonists on cartilage: a systematic review

OBJECTIVE

The aim of this study is to analyze the latest evidence on the effects of losartan or Ang II receptor antagonists on cartilage repair, with a focus on their clinical relevance.

DESIGN

The PubMed, Embase, and Cochrane Library databases were searched up to November 12th 2021 to evaluate the effects of losartan or Ang II receptor antagonists on cartilage repair in in vitro studies and in vivo animal studies. Study design, sample characteristics, treatment type, duration, and outcomes were analyzed. The risk of bias and the quality of the eligible studies were assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias assessment tool and Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES).

RESULTS

A total of 12 studies were included in this systematic review. Of the 12 eligible studies, two studies were in vitro human studies, three studies were in vitro animal studies, one study was an in vitro human and animal study, and six studies were in vivo animal studies. The risk bias and quality assessments were predominantly classified as moderate. Since meta-analysis was difficult due to differences in treatment type, dosage, route of administration, and method of outcome assessment among the eligible studies, qualitative evaluation was conducted for each study.

CONCLUSIONS

Both in vitro and in vivo studies provide evidence to demonstrate beneficial effects of Ang II receptor antagonists on osteoarthritis and cartilage defect models across animal species.

The Missouri Osteochondral Preservation System Is Associated With Better Short-Term Outcomes Than Standard Preservation Methods When Performing Osteochondral Allograft Transplantation Using Shell Grafts for Patellofemoral Lesions

PURPOSE

To compare outcomes after whole-surface osteochondral allograft (OCA) transplantation using shell grafts for treatment of patellofemoral joint lesions with respect to surfaces treated and OCA preservation method.

METHODS

With institutional review board approval and informed consent, patients were prospectively enrolled into a registry to follow outcomes after OCA transplantation. Patients who received patellofemoral shell OCA to treat the entire articular surface of the patella, trochlea, or both, and with a minimum of 2-year follow-up data, including patient-reported outcome measures (PROMs), failures, and complications, were included. Functional graft survival was determined based on patients returning to functional activities without need for OCA revision or arthroplasty surgery and calculated using the formula: 100% - (%revision + %failure). Minimum clinically important differences were determined based on previously validated data. Outcomes were compared based on differences in graft preservation methodology (Missouri Osteochondral Preservation System [MOPS] or standard preservation [SP]) and based on surfaces treated (patella, trochlea, or both).

RESULTS

Fifty-eight patients met inclusion criteria. Mean age was 36.7 years (range 15-60 years) and mean body mass index was 28.9 (range 18-42). OCAs stored using SP methods were transplanted in 12 patients, mean follow-up was (66.1 months; range 54-70 months): OCAs stored using MOPS methods were transplanted in 46 patients, mean follow-up was (44.8 months; range 24-60 months). Graft survival rate at final follow-up was significantly greater (P = .025) for MOPS OCAs (98%) compared with SP OCAs (75%), whereas 2-year functional graft survival rates (MOPS 98% vs SP 83%; P = .1) were not. Reoperation rate was significantly greater (P = .0014) for SP cases compared with MOPS cases. PROMs showed statistically significant and clinically meaningful improvements through 4 years after unipolar patella, unipolar trochlea, and bipolar patellofemoral OCA transplantation using MOPS grafts. Unipolar patella OCA transplantations were associated with significantly more reduction in pain and significantly better PROMs at 1-year compared with unipolar trochlea and bipolar patellofemoral OCAs.

CONCLUSIONS

OCA transplantation using MOPS shell grafts for unipolar and bipolar patellofemoral resurfacing was associated with statistically significant and clinically meaningful improvements from preoperative levels of pain and function. The 2-year functional graft survival rate was 83% in the SP group and 98% in the MOPS group, such that MOPS was associated with better short-term outcomes than SP methods when performing OCA transplantation using shell grafts for patellofemoral lesions. Patients who received unipolar patella allografts reported the best outcomes in terms of pain and function.

LEVEL OF EVIDENCE

Level III, retrospective analysis of registry data.

Biomechanical Properties of Repair Cartilage Tissue Are Superior Following Microdrilling Compared to Microfracturing in Critical Size Cartilage Defects

BACKGROUND/AIM

Common surgical treatment options for large focal chondral defects (FCDs) in the knee include microfracturing (MFX) and microdrilling (DRL). Despite numerous studies addressing MFX and DRL of FDCs, no in vivo study has focused on biomechanical analysis of repair cartilage tissue in critical size FCDs with different amounts of holes and penetration depths.

MATERIALS AND METHODS

Two round FCDs (d=6 mm) were created on the medial femoral condyle in 33 adult merino sheep. All 66 defects were randomly assigned to 1 control or 4 different study groups: 1) MFX1, 3 holes, 2 mm depth; 2) MFX2, 3 holes, 4 mm depth; 3) DRL1, 3 holes, 4 mm depth; and 4) DRL2, 6 holes, 4 mm depth. Animals were followed up for 1 year. Following euthanasia, quantitative optical analysis of defect filling was performed. Biomechanical properties were analysed with microindentation and calculation of the elastic modulus.

RESULTS

Quantitative assessment of defect filling showed significantly better results in all treatment groups compared to untreated FCDs in the control group (p<0.001), with the best results for DRL2 (84.2% filling). The elastic modulus of repair cartilage tissue in the DRL1 and DRL2 groups was comparable to the adjacent native hyaline cartilage, while significantly inferior results were identified in both MFX groups (MFX1: p=0.002; MFX2: p<0.001).

CONCLUSION

More defect filling and better biomechanical properties of the repair cartilage tissue were identified for DRL compared to MFX, with the best results for 6 holes and 4 mm of penetration depth. These findings are in contrast to the current clinical practice with MFX as the gold standard and suggest a clinical return to DRL.

Progress and prospect of technical and regulatory challenges on tissue-engineered cartilage as therapeutic combination product

Hyaline cartilage plays a critical role in maintaining joint function and pain. However, the lack of blood supply, nerves, and lymphatic vessels greatly limited the self-repair and regeneration of damaged cartilage, giving rise to various tricky issues in medicine. In the past 30 years, numerous treatment techniques and commercial products have been developed and practiced in the clinic for promoting defected cartilage repair and regeneration. Here, the current therapies and their relevant advantages and disadvantages will be summarized, particularly the tissue engineering strategies. Furthermore, the fabrication of tissue-engineered cartilage under research or in the clinic was discussed based on the traid of tissue engineering, that is the materials, seed cells, and bioactive factors. Finally, the commercialized cartilage repair products were listed and the regulatory issues and challenges of tissue-engineered cartilage repair products and clinical application would be reviewed.

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Tissue engineered cartilage, a promising strategy for articular cartilage repair.

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Nearly 20 engineered cartilage repair products in clinic based on clinical techniques.

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Combination product, the classification of tissue-engineered cartilage.

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Key regulatory compliance issues for combination products.

Double membrane platelet-rich fibrin (PRF) - Synovium succeeds in regenerating cartilage defect at the knee: An experimental study on rabbit

Background

This study aims to prove the healing results (regeneration) in cartilage defects using a combination treatment of microfractures and transplantation synovium-platelet rich fibrin (S-PRF).

Methods

A cartilage defect was made in the trochlear groove of the knee of adult New Zealand white rabbits, and was classified into three treatment groups. The group 1 was cartilage defect without treatment, 2 with microfracture treatment, and 3 with microfracture covered with a synovium-platelet rich fibrin (S-PRF) membrane. Twelve weeks after the intervention, the animals were macroscopically and histologically examined, and evaluated by the International Cartilage Repair Society (ICRS). Additionally, the expression of aggrecan and type 2 collagen was examined by real-time-PCR.

Results

The ICSR scores for macroscopic were significantly higher in the microfracture and S-PRF transplant group than in the other groups. Also, the ICSR scores for histology were significantly higher in this group. The expression of aggrecan and type 2 collagen was higher in the group that received complete treatment.

Conclusions

Microfractures and transplantation of synovium-platelet rich fibrin (S-PRF) can regenerate knee cartilage defects which have been shown to increase the expression of mRNA aggrecan and mRNA type 2 collagen resulting in excellent repair.

Cost Effectiveness of Allogeneic Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Patients with Knee Osteoarthritis

OBJECTIVES

The aim of this study was to assess the cost effectiveness of allogeneic umbilical cord blood-derived mesenchymal stem cells with sodium hyaluronate (hUCB-MSC) compared with microfracture in patients with knee cartilage defects caused by osteoarthritis (OA) in South Korea.

METHODS

A partitioned survival model approach was taken consisting of five mutually exclusive health states: excellent, good, fair, poor, and death over a 20-year time horizon. Utility values were obtained from a randomized clinical trial. Cost data were extracted from a database provided by the Health Insurance Review & Assessment Service, and the utilization of healthcare services was estimated from an expert panel of orthopedic surgeons using a structured questionnaire. The incremental cost-effectiveness ratio (ICER) in terms of quality-adjusted life-years (QALY) was calculated. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS

In the base case, the incremental costs of US$14,410 for hUCB-MSC therapy along with its associated QALY gain of 0.857 resulted in an ICER of US$16,812 (₩18,790,773) per QALY (95% confidence interval [CI] US$13,408-US$20,828) when compared with microfracture treatment from a healthcare payer perspective. From a societal perspective, the ICER was US$268 (₩299,255) per QALY (95% CI -US$2915 to US$3784). When using a willingness-to-pay threshold of US$22,367/QALY, the probability of hUCB being cost effectiveness compared with microfracture was 99% from the healthcare payer perspective and 100% from the societal perspective.

CONCLUSIONS

The study demonstrated that hUCB-MSC therapy was cost effective compared with microfracture when treating patients with knee OA. These findings should inform health policy decision makers about considerations for cost-effective therapy for treating knee OA to ultimately enhance population health.

Injectable Scaffold with Microfracture using the Autologous Matrix-Induced Chondrogenesis (AMIC) Technique: A Prospective Cohort Study

Introduction

Autologous matrix-induced chondrogenesis (AMIC) is a one-step surgical cartilage repair procedure involving the insertion of a scaffold into the chondral defect after microfracture. BST-CarGel [Smith and Nephew, Watford, England] is an injectable chitosan-based scaffold which can more easily fill defects with irregular shapes and be used to treat vertical or roof chondral lesions. The study aims to evaluate the clinical outcomes of knee cartilage repair with microfracture surgery and BST-CarGel using the AMIC technique for a minimum of two years.

Materials and methods

A prospective study of patients undergoing cartilage repair with microfracture surgery and BST-CarGel at our institution from 2016 to 2019 was performed. Clinical outcomes were determined using the Lysholm Knee Scoring System and Knee Injury and Osteoarthritis Outcome Score (KOOS). These questionnaires were administered before the surgery and at a minimum of two years after surgery.

Results

A total of 21 patients were identified and recruited into the study. 31 cartilage defects were seen and treated in 21 knees. These included horizontal lesions (e.g., trochlear, lateral tibial plateau), vertical lesions (e.g., medial femoral condyle, lateral femoral condyle) and inverted lesions (e.g., patella). No complications or reoperations were seen in our study population. For the average duration of follow-up of 42.5±8.55 months, there was an average improvement in Lysholm score of 25.8±18.6 and an average improvement in KOOS score of 22.5±15.0.

Conclusion

BST-CarGel with microfracture surgery using the AMIC technique is a safe and effective treatment for cartilage defects in the short to medium term.

Patients with Small Acetabular Cartilage Defects Caused by Femoroacetabular Impingement Do Not Benefit from Microfracture

OBJECTIVE

According to current recommendations, large cartilage defects of the hip over 2 cm2 are suggested to undergo autologous chondrocyte transplantation (ACT), while small defects should be treated with microfracture. We investigated if patients with small chondral defects of the hip joint (≤100 mm2) actually benefit from microfracture.

DESIGN

In this retrospective multicenter cohort study 40 patients with focal acetabular cartilage defects smaller than 100 mm2 and of ICRS grade ≥2 caused by femoroacetabular impingement were included. Twenty-six unrandomized patients underwent microfracture besides treatment of the underlying pathology; in 14 patients cartilage lesions were left untreated during arthroscopy. Over a mean follow-up of 28.8 months patient-reported outcome was determined using the iHOT33 (international hip outcome tool) and the VAS (visual analog scale) for pain.

RESULTS

The untreated group showed a statistically significant improvement of the iHOT33 after 12 (p = 0.005), 24 (p = 0.019), and 36 months (p = 0.002) compared to the preoperative score, whereas iHOT33 in the microfracture group did not reveal statistically significant changes over time. There was no significant difference between both groups on any time point. Regarding pain both groups did not show a significant improvement over time in the VAS.

CONCLUSION

The subjective outcome of patients with small cartilage defects of the hip (≤100 mm2) improves 12 months after arthroscopic FAIS surgery without any cartilage treatment. However, no improvement could be seen after microfracture. Therefore, a reserved surgical treatment for small cartilage defects of the hip under preservation of the subchondral bone is recommended especially if a simultaneous impingement correction is performed.

In Situ Assessment of Porcine Osteochondral Repair Tissue in the Visible-Near Infrared Spectral Region

Standard assessment of cartilage repair progression by visual arthroscopy can be subjective and may result in suboptimal evaluation. Visible-near infrared (Vis-NIR) fiber optic spectroscopy of joint tissues, including articular cartilage and subchondral bone, provides an objective approach for quantitative assessment of tissue composition. Here, we applied this technique in the 350-2,500 nm spectral region to identify spectral markers of osteochondral tissue during repair with the overarching goal of developing a new approach to monitor repair of cartilage defects in vivo. Full thickness chondral defects were created in Yucatan minipigs using a 5-mm biopsy punch, and microfracture (MFx) was performed as a standard technique to facilitate repair. Tissues were evaluated at 1 month (in adult pigs) and 3 months (in juvenile pigs) post-surgery by spectroscopy and histology. After euthanasia, Vis-NIR spectra were collected in situ from the defect region. Additional spectroscopy experiments were carried out in vitro to aid in spectral interpretation. Osteochondral tissues were dissected from the joint and evaluated using the conventional International Cartilage Repair Society (ICRS) II histological scoring system, which showed lower scores for the 1-month than the 3-month repair tissues. In the visible spectral region, hemoglobin absorbances at 540 and 570 nm were significantly higher in spectra from 1-month repair tissue than 3-month repair tissue, indicating a reduction of blood in the more mature repair tissue. In the NIR region, we observed qualitative differences between the two groups in spectra taken from the defect, but differences did not reach significance. Furthermore, spectral data also indicated that the hydrated environment of the joint tissue may interfere with evaluation of tissue water absorbances in the NIR region. Together, these data provide support for further investigation of the visible spectral region for assessment of longitudinal repair of cartilage defects, which would enable assessment during routine arthroscopy, particularly in a hydrated environment.

Intra-articular Damage and Patient Outcome Comparison Between Athletes and Nonathletes After Hip Arthroscopy

BACKGROUND

The body of literature comparing hip arthroscopy between athletes and nonathletes is relatively scarce. Analyzing these groups can help to shed light on the severity of intra-articular damage and end-stage osteoarthritis that may result from participation in strenuous activities.

PURPOSE

(1) To compare the intra-articular damage at the time of hip arthroscopy between athletes and nonathletes, and (2) to compare the pre- and postoperative outcomes between the groups.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients were considered eligible for analysis if they had received a primary hip arthroscopy between August 2008 and June 2018, were participating in competitive athletics, and had preoperative baseline scores and minimum 2-year follow-up for the following patient-reported outcomes: modified Harris Hip Score, Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sports Specific Subscale, and visual analog scale. Propensity score matching was used to match eligible patients in a 1:1 ratio to patients who were not participating in any sports greater than a recreational level before surgery.

RESULTS

A total of 234 patients were included. There were no significant differences in the severity of labral tears, ligamentum teres tears, or cartilage damage (P > .05). The procedures performed between cohorts were similar (P > .05). The athlete population had higher preoperative means scores for the modified Harris Hip Score and NAHS (each P < .001). Likewise, the athlete population had higher postoperative means scores for the NAHS, Hip Outcome Score-Sports Specific Subscale, and visual analog scale (P = .031, P = .030, and P = .032, respectively). Additionally, the athlete cohort reported higher minimum 2-year outcomes than the nonathlete cohort for the 12-Item Short Form Health Survey (mental component; P = .003) and Veterans RAND 12-Item Health Survey (mental component, P = .032; physical component, P = .005).

CONCLUSION

At the time of hip arthroscopy, athletes demonstrate similar intra-articular damage to their nonathlete counterparts. Given their higher preoperative scores, it is possible that athletes better tolerate the damage to the hip joint. Despite their strenuous activities and potentially higher tolerance to pain, athletes should not necessarily be expected to have greater severity of intra-articular pathology.

Effects of oral losartan administration on homeostasis of articular cartilage and bone in a rabbit model

Background and aims

Previous work has shown that oral losartan can enhance microfracture-mediated cartilage repair in a rabbit osteochondral defect injury model. In this study, we aimed to determine whether oral losartan would have a detrimental effect on articular cartilage and bone homeostasis in the uninjured sides.

Methods

New Zealand rabbits were divided into 4 groups including normal uninjured (Normal), contralateral uninjured side of osteochondral defect (Defect), osteochondral defect plus microfracture (Microfracture) and osteochondral defect plus microfracture and losartan oral administration (10 mg/kg/day) (Losartan). Rabbits underwent different surgeries and treatment and were sacrificed at 12 weeks. Both side of the normal group and uninjured side of treatment groups tibias were harvested for Micro-CT and histological analysis for cartilage and bone including H&E staining, Herovici's staining (bone and cartilage) Alcian blue and Safranin O staining (cartilage) as well as immunohistochemistry of losartan related signaling pathways molecules for both cartilage and bone.

Results

Our results showed losartan oral treatment at 10 mg/kg/day slightly increase Alcian blue positive matrix as well as decrease collagen type 3 in articular cartilage while having no significant effect on articular cartilage structure, cellularity, and other matrix. Losartan treatment also did not affect angiotensin receptor type 1 (AGTR1), angiotensin receptor type 2 (AGTR2) and phosphorylated transforming factor β1 activated kinase 1 (pTAK1) expression level and pattern in the articular cartilage. Furthermore, losartan treatment did not affect microarchitecture of normal cancellous bone and cortical bone of tibias compared to normal and other groups. Losartan treatment slightly increased osteocalcin positive osteoblasts on the surface of cancellous bone and did not affect bone matrix collagen type 1 content and did not change AGTR1, AGTR2 and pTAK1 signal molecule expression.

Conclusion

Oral losartan used as a microfracture augmentation therapeutic does not have significant effect on uninjured articular cartilage and bone based on our preclinical rabbit model. These results provided further evidence that the current regimen of using losartan as a microfracture augmentation therapeutic is safe with respect to bone and cartilage homeostasis and support clinical trials for its application in human cartilage repair.

Platelet-Rich Plasma and Adipose-Derived Mesenchymal Stem Cells in Association with Arthroscopic Microfracture of Knee Articular Cartilage Defects: A Pilot Randomized Controlled Trial

Background

This study aims to compare the effects of platelet-rich plasma (PRP) alone or in combination with adipose-derived mesenchymal stem cells (AD-MSCs) in patients affected by cartilage defects, undergoing knee arthroscopic microfracture.

Methods

Thirty-eight patients diagnosed with a knee monocompartmental cartilage defect (Outerbridge grade IV) on the MRI, underwent an arthroscopic procedure. After the confirmation of the lesion, they all received the same bone marrow stimulation technique (microfracture) and were randomized into two groups: the first one had additional PRP injection (group A), while the second received PRP and AD-MSC injection (group B). Knee assessment and pain score were documented with Knee Injury Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, Short-Form (SF) 12, and Visual Analogue Scale (VAS) before the treatment and at 1, 3, 6, and 12 months of follow-up postoperatively. An additional arthroscopic procedure, performed in four patients for a subsequent meniscal lesion, let us evaluate cartilage evolution by performing a macro/microscopical assessment on cartilage biopsy specimens.

Results

At the 12-month follow-up, both groups showed a comparable functional improvement. The scores on the IKDC form, KOOS, pain VAS, and SF-12 significantly improved from baseline (p < 0.05) to 12 months postoperatively in both treatment groups. The four second-look arthroscopies showed a complete repair of the articular defects by smooth solid cartilage layer, with a good chondrocytic population, in both groups. A thick smooth hyaline-like cartilage with a predominantly viable cell population and normal mineralization (a form closely resembling native tissue) was observed in group B.

Conclusions

Modern regenerative medicine techniques, such as PRP and AD-MSC, associated with traditional arthroscopic bone marrow stimulating techniques, seem to enhance cartilage restoration ability. The preliminary results of this pilot study encourage the synergic use of these regenerative modulating systems to improve the quality of the regenerated cartilage.

Effect of Platelet-Rich Plasma on Autologous Chondrocyte Implantation for Chondral Defects: Results Using an In Vivo Rabbit Model

Background:

Articular cartilage repair remains challenging despite the availability of techniques, including autologous chondrocyte implantation (ACI) for repairing large cartilage defects. Platelet-rich plasma (PRP) therapy, a novel therapy focused on chondrocyte regeneration, needs to be investigated regarding its potential to improve the outcomes of ACI.

Purpose:

To examine the effect of PRP therapy on the outcomes of cartilage repair using the ACI procedure in a rabbit model of knee joint cartilage damage.

Study Design:

Controlled laboratory study.

Methods:

A total of 30 knees in 15 Japanese White rabbits (joint cartilage damage model) were divided into nontreatment (n = 7), PRP (n = 8), ACI (n = 7), and combined ACI and PRP (n = 8) groups. At 4 weeks and 12 weeks postoperatively, histological and visual examination of the surgical site was performed, and the regenerated cartilage and calcified bone areas were measured by imaging the specimens.

Results:

Pretransplantation evaluation in the cultured cartilage showed the histological properties of hyaline cartilage. At 4 weeks postoperatively, the regenerated cartilage area at the surgical site showed a larger safranin O–positive area in the ACI group (2.73 ± 4.46 mm²) than in the combined ACI and PRP group (1.71 ± 2.04 mm²). Calcified bone formation in the ACI group was relatively lower than that in the other groups. Cartilage repair failure occurred in all groups at 12 weeks postoperatively.

Conclusion:

The authors found no positive effects of PRP on the outcomes of ACI in a rabbit model. There was a smaller safranin O–positive region with the addition of PRP to ACI compared with ACI alone. In the subchondral bone, bone formation might have been promoted by PRP.

Clinical Relevance:

Administering PRP at the time of ACI may not have a positive effect and may have deleterious effects on cartilage engraftment and regeneration.

Recombinant fibroblast growth factor-18 (sprifermin) enhances microfracture-induced cartilage healing

Posttraumatic osteoarthritis is a disabling condition impacting the mostly young and active population. In the present study, we investigated the impact of intra-articular sprifermin, a recombinant truncated fibroblast growth factor 18, on the outcome of microfracture treatment, a widely used surgical technique to enhance cartilage healing at the site of injury. For this study, we created a cartilage defect and performed microfracture treatment in fetlock joints of 18 horses, treated joints with one of three doses of sprifermin (10, 30, or 100 μg) or with saline, hyaluronan, and evaluated animals functional and structural outcomes over 24 weeks. For primary outcome measures, we performed histological evaluations and gene expression analysis of aggrecan, collagen types I and II, and cartilage oligomeric matrix protein in three regions of interest. As secondary outcome measures, we examined animals' lameness, performed arthroscopic, radiographic, and computed tomography (CT) scan imaging and gross morphology assessment. We detected the highest treatment benefit following 100 μg sprifermin treatment. The overall histological assessment showed an improvement in the kissing region, and the expression of constitutive genes showed a concentration-dependent enhancement, especially in the peri-lesion area. We detected a significant improvement in lameness scores, arthroscopic evaluations, radiography, and CT scans following sprifermin treatment when results from three dose-treatment groups were combined. Our results demonstrated, for the first time, an enhancement on microfracture outcomes following sprifermin treatment suggesting a cartilage regenerative role and a potential benefit of sprifermin treatment in early cartilage injuries.

Limited medial osteochondral lesions of the talus associated with chronic ankle instability do not impact the results of endoscopic modified Broström ligament repair

Background

The arthroscopic modified Broström procedure, with repair of the anterior talofibular ligament and extensor retinaculum, produces good functional outcomes in patients with chronic lateral ankle instability (CLAI). CLAI can be associated with osteochondral lesions of the talus (OLTs). It remains unclear whether associated limited OLTs affect clinical outcomes in such patients.

Methods

This retrospective cohort study included 92 CLAI patients with and without OLTs undergoing an all-inside arthroscopic modified Broström procedure from June 2016 to May 2019. The patients were divided into non-lesion group (n = 32) and lesion group (n = 60) according to whether CLAI was associated or not with OLTs. All the osteochondral lesions less than 15 mm in diameter were managed with bone marrow stimulation techniques (arthroscopic microfracture) at the time of the arthroscopic modified Broström procedure. The Visual Analogue Scale (VAS) scores, American Orthopedic Foot and Ankle Society (AOFAS) scores, Karlsson Ankle Function Score (KAFS), Anterior Talar Translation (ATT), Active Joint Position Sense (AJPS), and the rate of return to sports were compared in both groups.

Results

Increase in all the functional scores (VAS, AOFAS, KAFS, ATT, and AJPS) in both groups was, respectively, recorded 1 year and 2 years after surgery. At the 1-year and 2-year follow-up, there was no significant difference in the VAS, AOFAS, KAFS, ATT, and AJPS scores between the non-lesion and lesion groups.

Conclusion

In patients with CLAI who underwent an arthroscopic modified Broström procedure, the presence of limited OLTs (less than 15 mm in diameter), which required arthroscopic microfracture, did not exert any influence on outcome.

Level of Evidence

Level III, a retrospective comparative study.

The Effect of Bone Marrow Stimulation for Cartilage Repair on the Subchondral Bone Plate

PURPOSE

To investigate the effect of bone-marrow stimulation (BMS) on subchondral bone plate morphology and remodeling compared to untreated subchondral bone in a validated minipig model.

METHODS

Three Göttingen minipigs received BMS with drilling as treatment for two chondral defects in each knee. The animals were euthanized after six months. Follow-up consisted of a histological semiquantitative evaluation using a novel subchondral bone scoring system and micro computed tomography (µCT) of the BMS subchondral bone. The histological and microstructural properties of the BMS-treated subchondral bone were compared to that of the adjacent healthy subchondral bone.

RESULTS

The µCT analysis showed that subchondral bone treated with BMS had significantly higher connectivity density compared to adjacent untreated subchondral bone (26 1/mm³ vs. 21 1/mm³, P = 0.048). This was the only microstructural parameter showing a significant difference. The histological semiquantitative score differed significantly between the subchondral bone treated with BMS and the adjacent untreated subchondral (8.0 vs. 10 P = < 0.001). Surface irregularities were seen in 43% and bone overgrowth in 27% of the histological sections. Only sparse formation of bone cysts was detected (1%).

CONCLUSIONS

BMS with drilling does not cause extensive changes to the subchondral bone microarchitecture. Furthermore, the morphology of BMS subchondral bone resembled that of untreated subchondral bone with almost no formation of bone cyst, but some surface irregularities and bone overgrowth.

Focal articular surface replacement as primary treatment for focal chondral defects of the femoral condyles: A series of 157 cases

BACKGROUND

Focal chondral defects (FCDs) of the femoral condyle are common. Treatment has heretofore primarily consisted of non-surgical and biological treatments. Focal articular surface replacement (FASR) is an emerging technique utilizing small implants to essentially fill the FCD. Here we report functional outcome and re-operation rates following FASR as a primary treatment for FCDs of the femoral condyles.

METHODS

Retrospective analysis of a prospectively collected database including 327 FASR procedures was performed to identify patients who underwent FASR of the femoral condyle with a modular cementless metallic implant (HemiCAP^TM) as a primary procedure. Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), SF-36 Health Status Survey (SF-36) and Visual Analog Scale (VAS) were collected before and 6 weeks, 6 months, and 4 years after surgery. Implant revision and re-operation rate were recorded.

RESULTS

157 patients were included with a mean follow-up of 9.4 ± 1.3 years (range 7.0 to 11.4 years). The average age was 40.2 ± 5.3 years, 85% involved the medial condyle, and the average defect size was 3.6 ± 0.5 cm². Primary FASR resulted in functional improvement on the KOOS (+52%), OKS (+69%) and SF-36 (+50%) scores and a reduction in VAS scores (-70%) at 4-year follow-up. Revision rate was 0.64% and the re-operation rate was 11%.

CONCLUSION

This retrospective case-series supports primary FASR with HemiCAP^TM implants as an alternative to biological procedures to treat medium-sized FCDs (2.5-4 cm²) of the femoral condyle, although long-term follow-up is necessary to determine if the clinical outcome and low revision rate can be maintained.

Algorithm for Treatment of Focal Cartilage Defects of the Knee: Classic and New Procedures

OBJECTIVE

To create a treatment algorithm for focal grade 3 or 4 cartilage defects of the knee using both classic and novel cartilage restoration techniques.

DESIGN

A comprehensive review of the literature was performed highlighting classic as well as novel cartilage restoration techniques supported by clinical and/or basic science research and currently being employed by orthopedic surgeons.

RESULTS

There is a high level of evidence to support the treatment of small to medium size lesions (<2-4 cm2) without subchondral bone involvement with traditional techniques such as marrow stimulation, osteochondral autograft transplant (OAT), or osteochondral allograft transplant (OCA). Newer techniques such as autologous matrix-induced chondrogenesis and bone marrow aspirate concentrate implantation have also been shown to be effective in select studies. If subchondral bone loss is present OAT or OCA should be performed. For large lesions (>4 cm2), OCA or matrix autologous chondrocyte implantation (MACI) may be performed. OCA is preferred over MACI in the setting of subchondral bone involvement while cell-based modalities such as MACI or particulated juvenile allograft cartilage are preferred in the patellofemoral joint.

CONCLUSIONS

Numerous techniques exist for the orthopedic surgeon treating focal cartilage defects of the knee. Treatment strategies should be based on lesion size, lesion location, subchondral bone involvement, and the level of evidence supporting each technique in the literature.

Combination of a Collagen Scaffold and an Adhesive Hyaluronan-Based Hydrogel for Cartilage Regeneration: A Proof of Concept in an Ovine Model

OBJECTIVE

Hyaluronic acid-transglutaminase (HA-TG) is an enzymatically crosslinkable adhesive hydrogel with chondrogenic properties demonstrated in vitro and in an ectopic mouse model. In this study, we investigated the feasibility of using HA-TG in a collagen scaffold to treat chondral lesions in an ovine model, to evaluate cartilage regeneration in a mechanically and biologically challenging joint environment, and the influence of the surgical procedure on the repair process.

DESIGN

Chondral defects of 6-mm diameter were created in the stifle joint of skeletally mature sheep. In a 3-month study, 6 defects were treated with HA-TG in a collagen scaffold to test the stability and biocompatibility of the defect filling. In a 6-month study, 6 sheep had 12 defects treated with HA-TG and collagen and 2 sheep had 4 untreated defects. Histologically observed quality of repair tissue and adjacent cartilage was semiquantitatively assessed.

RESULTS

HA-TG adhered to the native tissue and did not cause any detectable negative reaction in the surrounding tissue. HA-TG in a collagen scaffold supported infiltration and chondrogenic differentiation of mesenchymal cells, which migrated from the subchondral bone through the calcified cartilage layer. Additionally, HA-TG and collagen treatment led to better adjacent cartilage preservation compared with empty defects (P < 0.05).

CONCLUSIONS

This study demonstrates that the adhesive HA-TG hydrogel in a collagen scaffold shows good biocompatibility, supports in situ cartilage regeneration and preserves the surrounding cartilage. This proof-of-concept study shows the potential of this approach, which should be further considered in the treatment of cartilage lesions using a single-step procedure.

Arthroscopic Matrix-Encapsulated Autologous Chondrocyte Implantation: A Pilot Multicenter Investigation in Latin America

Objective. To evaluate minimum biosecurity parameters (MBP) for arthroscopic matrix-encapsulated autologous chondrocyte implantation (AMECI) based on patients' clinical outcomes, magnetic resonance imaging (MRI) T2-mapping, Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, and International Cartilage Repair Society (ICRS) second-look arthroscopic evaluation, laying the basis for a future multicenter study. Design. Pilot clinical study. We analyzed the logistics to perform AMECI to treat focal chondral lesions in different hospitals following strict biosecurity parameters related to tissue and construct transportation, chondrocyte isolation, and cell expansion. Patient progress was analyzed with patient-reported outcome measures, MRI T2-mapping, MOCART, and ICRS arthroscopic second-look evaluation. Results. Thirty-five lesions in 30 patients treated in 7 different hospitals were evaluated. Cell viability before implantation was >90%. Cell viability in construct remnants was 87% ± 11% at 24 hours, 75% ± 17.1% at 48 hours, and 60% ± 8% at 72 hours after implantation. Mean final follow-up was 37 months (12-72 months). Patients showed statistically significant improvement in all clinical scores and MOCART evaluations. MRI T2-mapping evaluation showed significant decrease in relaxation time from 61.2 ± 14.3 to 42.9 ± 7.2 ms (P < 0.05). Arthroscopic second-look evaluation showed grade II "near normal" tissue in 83% of patients. Two treatment failures were documented. Conclusions. It was feasible to perform AMECI in 7 different institutions in a large metropolitan area following our biosecurity measures without any implant-related complication. Treated patients showed improvement in clinical, MRI T2-mapping, and MOCART scores, as well as a low failure rate and a favorable ICRS arthroscopic evaluation at a mid-term follow-up. Level of Evidence. 2b.

3D Printed Multiphasic Scaffolds for Osteochondral Repair: Challenges and Opportunities

Osteochondral (OC) defects are debilitating joint injuries characterized by the loss of full thickness articular cartilage along with the underlying calcified cartilage through to the subchondral bone. While current surgical treatments can provide some relief from pain, none can fully repair all the components of the OC unit and restore its native function. Engineering OC tissue is challenging due to the presence of the three distinct tissue regions. Recent advances in additive manufacturing provide unprecedented control over the internal microstructure of bioscaffolds, the patterning of growth factors and the encapsulation of potentially regenerative cells. These developments are ushering in a new paradigm of 'multiphasic' scaffold designs in which the optimal micro-environment for each tissue region is individually crafted. Although the adoption of these techniques provides new opportunities in OC research, it also introduces challenges, such as creating tissue interfaces, integrating multiple fabrication techniques and co-culturing different cells within the same construct. This review captures the considerations and capabilities in developing 3D printed OC scaffolds, including materials, fabrication techniques, mechanical function, biological components and design.

Cell-laden injectable microgels: Current status and future prospects for cartilage regeneration

Injectable hydrogels have been employed extensively as versatile materials for cartilage regeneration due to their excellent biocompatibility, tunable structure, and ability to accommodate bioactive factors, as well as their ability to be locally delivered via minimally invasive injection to fill irregular defects. More recently, in vitro and in vivo studies have revealed that processing these materials to produce cell-laden microgels can enhance cell-cell and cell-matrix interactions and boost nutrient and metabolite exchange. Moreover, these studies have demonstrated gene expression profiles and matrix regeneration that are superior compared to conventional injectable bulk hydrogels. As cell-laden microgels and their application in cartilage repair are moving closer to clinical translation, this review aims to present an overview of the recent developments in this field. Here we focus on the currently used biomaterials and crosslinking strategies, the innovative fabrication techniques being used for the production of microgels, the cell sources used, the signals used for induction of chondrogenic differentiation and the resultant biological responses, and the ability to create three-dimensional, functional cartilage tissues. In addition, this review also covers the current clinical approaches for repairing cartilage as well as specific challenges faced when attempting the regeneration of damaged cartilage tissue. New findings related to the macroporous nature of the structures formed by the assembled microgel building blocks and the novel use of microgels in 3D printing for cartilage tissue engineering are also highlighted. Finally, we outline the challenges and future opportunities for employing cell-laden microgels in clinical applications.

Long-term Patient-Reported Outcome Measures Following Particulated Juvenile Allograft Cartilage Implantation for Treatment of Difficult Osteochondral Lesions of the Talus

BACKGROUND

Conventional methods are not suitable for difficult to treat osteochondral lesions of the talus (OCLTs). The role of particulated juvenile allograft articular cartilage implantation is not well elucidated for long-term patient outcomes.

METHODS

Thirteen patients with difficult-to-treat OCLTs underwent arthroscopy-assisted implantation of particulated juvenile articular cartilage graft into defects from 2010 to 2012 by the same surgeon. "Difficult to treat" was defined as having at least 3 of the following features or 2 if both variables described lesion characteristics: (1) lesions size of 107 mm² or greater, (2) shoulder lesions, (3) patients who failed microfracture, (4) patient aged ≥40 years, or (5) patient body mass index (BMI) >25. Patients were evaluated using physical examination, patient interviews, and outcome score measures. Patients had follow-up at 2 years, 4 years, and between 6 and 10 years at their most recent follow-up. Differences in functional outcome scores were compared before and after surgery.

RESULTS

Patients (age: 46.5 ± 11.8 years, BMI: 28.5 ± 6.1) had, on average, most recent follow-up of 8.0 years (range 72-113 months). Average visual analog scale for pain score decreased for patients by 3.9 points (95% confidence interval [CI] 2.18-5.60), when compared to preoperative assessment. Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) and Sports subscale scores also improved from 46.5 to 80.9 (95% CI 21.35-47.43), and from 18.8 to 57.9 (95% CI 21.05-57.10), respectively. Short Form-36 Health Survey physical component scores showed significant improvement by an average of 45.5 points (95% CI 32.42-58.50). American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Scale scores improved from 55.2 to 80.3 (95% CI 12.459-37.741).

CONCLUSION

These results demonstrate positive patient-reported long-term outcomes for a cohort of patients with difficult OCLTs, followed over the course of 6-10 years after treatment with arthroscopy-assisted particulated juvenile articular cartilage implantation.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Role of the osteochondral unit in the pathogenesis of osteoarthritis: focus on the potential use of clodronate

Osteoarthritis (OA) is a chronic disease characterized by inflammation and progressive deterioration of the joint. The etiology of OA includes genetic, phlogistic, dismetabolic and mechanical factors. Historically, cartilage was considered the target of the disease and therapy was aimed at protecting and lubricating the articular cartilage. The osteochondral unit is composed of articular cartilage, calcified cartilage, and subchondral and trabecular bone, which work synergistically to support the functional loading of the joint. Numerous studies today show that OA involves the osteochondral unit, with the participation therefore of the bone in the starting and progression of the disease, which is associated with chondropathy. Cytokines involved in the process leading to cartilage damage are also mediators of subchondral bone edema. Therefore, OA therapy must be based on the use of painkillers and bisphosphonates for both the control of osteometabolic damage and its analgesic activity. Monitoring of the disease of the osteochondral unit must be extensive, since bone marrow edema can be considered as a marker of the evolution of OA. In the present review we discuss some of the pathogenetic mechanisms associated with osteoarthritis, with particular focus on the osteochondral unit and the use of clodronate.

Medial and Lateral Patellar Instability Leading to Medial Patellofemoral Ligament and Lateral Retinaculum Reconstruction: A Case Report

CASE

Combined medial and lateral patellar instability is exceptionally rare with only 3 reported cases to date. Here, we present the case of a 37-year-old White woman with multiple recurrent medial and lateral patellar instability. After failure of conservative care with bracing and therapy, she underwent surgical stabilization with medial and lateral allograft reconstruction.

CONCLUSION

This case provides an example of the condition and successful surgical follow-up.

Chondroinductive Peptides for Cartilage Regeneration

Inducing and maintaining a hyaline cartilage phenotype is the greatest challenge for cartilage regeneration. Synthetic chondroinductive biomaterials might be the answer to the unmet clinical need for a safe, stable, and cost-effective material capable of inducing true hyaline cartilage formation. The past decade witnessed an emergence of peptides to achieve chondrogenesis, as peptides have the advantages of versatility, high target specificity, minimized toxicity and immunogenicity, and ease of synthesis. Here, we review peptides as the basis for creating promising synthetic chondroinductive biomaterials for in situ scaffold-based cartilage regeneration. We provide a thorough review of peptides evaluated for cartilage regeneration while distinguishing between peptides reported to induce chondrogenesis independently, and peptides reported to act in synergy with other growth factors to induce cartilage regeneration. Additionally, we highlight that most peptide studies have been in vitro, and appropriate controls are not always present. A few rigorously-performed in vitro studies have proceeded to in vivo studies, but the peptides in those in vivo studies were mainly introduced via systemic, subcutaneous, or intraarticular injections, with a paucity of studies employing in situ defects with appropriate controls. Clinical translation of peptides will require the evaluation of these peptides in well-controlled in vivo cartilage defect studies. In the decade ahead, we may be poised to leverage peptides to design devices that are safe, reproducible, cost-efficient, and scalable biomaterials, which are themselves chondroinductive to achieve true hyaline cartilage regeneration without the need for growth factors and other small molecules.

From Cells to Organs: The Present and Future of Regenerative Medicine

Regenerative medicine promises a bright future where damaged body parts can be restored, rejuvenated, and replaced. The application of regenerative medicine is interdisciplinary and covers nearly all fields of medical sciences and molecular engineering. This review provides a road map on how regenerative medicine is applied on the levels of cell, tissue, and organ and summarizes the advantages and limitation of human pluripotent stem cells in disease modeling and regenerative application.

Outcomes of rotator cuff repair with concurrent microfracture of focal glenohumeral osteoarthritis

BACKGROUND

The benefit of rotator cuff repair (RCR) in patients with concurrent osteoarthritic changes remains unclear. RCR has the theoretical potential to increase the compressive force across the glenohumeral joint, further exacerbating osteoarthritis pain. The purpose of this study is to investigate pain relief and patient-reported outcomes of patients undergoing simultaneous RCR and microfracture of focal glenohumeral osteoarthritis.

METHODS

Thirty-four patients undergoing simultaneous RCR and microfracture were retrospectively reviewed at a minimum 1-year follow-up. Patient demographics, preoperative range of motion, functional outcomes (visual analog scale [VAS], Single Assessment Numeric Evaluation [SANE], American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES], and Simple Shoulder Test [SST]), and operative metrics were recorded. The patients were then contacted to obtain postoperative functional outcome scores (VAS, SANE, ASES, and SST).

RESULTS

Twenty-seven patients (11 male/16 female [79%]) were evaluated at a mean follow-up of 25.8 months (range, 12-46). The average age at surgery was 64.9 years (range, 56-78). Chronic tears were more common than acute tears (57.7% vs. 42.3%). The majority of patients had a full rotator cuff tear (89%) involving a mean 1.7 ± 0.8 tendons (range, 1-3). Eighty-eight percent of the humeral lesions were Outerbridge 4 compared with 84% on the glenoid. The mean estimated involvement between the 2 groups with 38.4% ± 18.4% of the humeral head involved and 34.6% ± 18.4% of the glenoid involved. PRO scores improved postoperatively with a reduction in mean VAS (6.6-2.0, P < .01), SANE (33.8-79.8, P < .01), ASES (38.0-80.9, P < .01), and SST (3.07-9.70, P < .01) scores. Cumulatively, only 52% (14/27) of the patients improved, however, by the MCID for all collected PROs.

CONCLUSIONS

Our results demonstrate modest improvements in postoperative pain and functional scores at a minimum of 1-year follow-up in a cohort of patients who have undergone RCR and glenohumeral microfracture. In cases of small focal lesions of full-thickness cartilage loss, RCR with microfracture is a reasonable treatment option; however, patients should be counseled on expectations accordingly.

Using apheresis-derived cells to augment microdrilling in the treatment of chondral defects in an ovine model

The treatment of chondral defects using microdrilling often results in a mechanically weak fibrocartilagenous repair, rather than a more robust hyaline cartilage repair. Many different microfracture/microdrilling augmentation techniques have been described, including the use of cellular products to enhance healing. Autologous peripheral blood progenitor cells can be obtained via apheresis after administration of granulocyte colony-stimulating factor (G-CSF) and have been used successfully to augment microdrilling in clinical patients. The objective of this study was to use apheresis-derived mononuclear blood cells to augment microdrilling treatment of a cartilage defect in an ovine model to determine the effect on healing. Forty adult female sheep were used in this study and were divided into a control group (microdrilling alone) and a treatment group (microdrilling, hyaluronic acid, and apheretic product). Outcome measurements included weight-bearing on the operated limb, macroscopic scoring of the joint, histology, and immunohistochemistry. In addition, magnetic resonance imaging was used to attempt to identify SPION-labeled cells from the apheretic product in the operated limbs. The results showed a significant increase in healing as measured by the modified O'Driscoll sore in the treated group. No evidence of homing of SPION-labeled cells to the defect was found and no correlation was found between the response to G-CSF administration or concentration of CD34⁺  and outcome. A correlation was found between healing and the concentration of white blood cells and peripheral blood mononuclear cell numbers in the apheretic product.

Crosstalk Between Mesenchymal Stromal Cells and Chondrocytes: The Hidden Therapeutic Potential for Cartilage Regeneration

Cartilage injuries following trauma create a puzzling clinical scenario. The finite reparative potential of articular cartilage is well known, and injuries are associated with an increased risk of osteoarthritis. Cell-based therapies have spotlighted chondrocytes and mesenchymal stromal cells (MSCs) as the functional unit of articular cartilage and the progenitor cells, respectively. The available clinical treatments cannot reproduce the biomechanical properties of articular cartilage and call for continuous investigations into alternative approaches. Co-cultures of chondrocytes and MSCs are an attractive in vitro system to step closer to the in vivo multicellular environment's complexity. Research on the mechanisms of interaction between both cell types will reveal essential cues to understand cartilage regeneration. This review describes the latest discoveries on these interactions, along with advantages and main challenges in vitro and in vivo. The successful clinical translation of in vitro studies requires establishing rigorous standards and clinically relevant research models and an organ-targeting therapeutic strategy.

Identification of Candidate Synovial Fluid Biomarkers for the Prediction of Patient Outcome After Microfracture or Osteotomy

BACKGROUND

Biomarkers are needed to predict clinical outcomes for microfracture and osteotomy surgeries to ensure patients can be better stratified to receive the most appropriate treatment.

PURPOSE

To identify novel biomarker candidates and to investigate the potential of a panel of protein biomarkers for the prediction of clinical outcome after treatment with microfracture or osteotomy.

STUDY DESIGN

Descriptive laboratory study.

METHODS

To identify novel candidate biomarker proteins, we used label-free quantitation after liquid chromatography-tandem mass spectrometry of dynamic range-compressed synovial fluids (SFs) from individuals who responded excellently or poorly (based on change in Lysholm score) to microfracture (n = 6) or osteotomy (n = 7). Biomarkers that were identified in this proteomic analysis or that relate to osteoarthritis (OA) severity or have predictive value in another early OA therapy (autologous cell implantation) were measured in the SF of 19 and 13 patients before microfracture or osteotomy, respectively, using commercial immunoassays, and were normalized to urea. These were aggrecanase-1 (ADAMTS-4), cartilage oligomeric matrix protein (COMP), hyaluronan (HA), lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), matrix metalloproteinase 1 and 3, soluble CD14, S100 calcium binding protein A13, and 14-3-3 protein theta (YWHAQ). Levels of COMP and HA were also measured in the plasma of these patients. To find predictors of postoperative function, multivariable regression analyses were performed.

RESULTS

Proteomic analyses highlighted YWHAQ and LYVE-1 as being differentially abundant between the clinical responders/improvers and nonresponders after microfracture. A linear regression model after backward variable selection could relate preoperative concentrations of SF proteins (HA, YWHAQ, LYVE-1), activity of ADAMTS-4, and patient demographic characteristics (smoker status and sex) with Lysholm score 12 months after microfracture. Further, a generalized linear model with elastic net penalization indicated that lower preoperative activity of ADAMTS-4 in SF, being a nonsmoker, and being younger at the time of operation were indicative of a higher postoperative Lysholm score (improved joint function) after osteotomy surgery.

CONCLUSION

We have identified biomarkers and generated regression models with the potential to predict clinical outcome in patients treated with microfracture or osteotomy of the knee.

CLINICAL RELEVANCE

Candidate protein biomarkers identified in this study have the potential to help determine which patients will be best suited to treatment with microfracture or osteotomy.

Microdrilling Demonstrates Superior Patient-Reported Outcomes and Lower Revision Rates Than Traditional Microfracture: A Matched Cohort Analysis

Purpose

The purpose of this study was to compare patient-reported outcomes and revision rates between the standard microfracture awl versus the microdrilling technique.

Methods

Microfracture patients were queried from a single-institution database between 2001 and 2016. Patient-reported outcome measure data were collected at preoperative and 6- and 12-month time points, inclusive of the International Knee Documentation Committee (IKDC) score, Short Form 12 (SF12) Physical Component Score (PCS) and Mental Component Score, and all Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales. A matching algorithm based on previous procedures, lesion size, and demographic factors created 2 technique-based cohorts. Outcomes including revision rates and both statistically and clinically significant differences (i.e., the minimally clinically important difference [MCID]) between awl and microdrill cohorts were compared using univariate statistics.

Results

A total of 68 patients (aged 32.0 ± 13.1 years, 48.5% female, body mass index 26.7 ± 5.3 kg/m²), with 34 patients in each group, were included after the match. At 6 months, the microdrilling group demonstrated significantly greater levels of improvement than the awl group on the IKDC, SF12 PCS, and KOOS Pain, Symptom, Sport, and Quality of Life (P < .04), although differences at 1 year were only maintained on the SF12 PCS instrument (P < .001). With respect to MCID achievement, the microdrilling group demonstrated greater achievement rates at 6 months on the IKDC, KOOS Pain, and KOOS Sport (P < .04). The awl group demonstrated a higher rate of revision surgery (P = .02) within 3 years of follow-up and a greater likelihood to require multiple subsequent procedures (41.1% vs 17.6%, P = .03).

Conclusions

Microdrilling demonstrated superior outcomes relative to traditional microfracture awl techniques with respect to patient-reported outcomes at 6 months and revision rates within 3 years of follow-up. In addition, clinically meaningful differences were evident at 6 months in the microdrilling group.

Level of Evidence

Level III, retrospective comparative study.

Postoperative Management for Articular Cartilage Surgery in the Knee

The postoperative rehabilitation team plays a crucial role in optimizing outcomes after articular cartilage surgery. A comprehensive approach to postoperative physical therapy that considers the type of surgery, location in the knee, concurrent procedures, and patient-specific factors is imperative. While postoperative rehabilitation protocols should be specific to the patient and type of surgery performed and include phased rehabilitation goals and activities, the key principles for postoperative rehabilitation apply across the spectrum of articular cartilage surgeries and patients. These key principles consist of preoperative assessments that include physical, mental, and behavioral components critical to recovery; education and counseling with respect to expectations and compliance; and careful monitoring and adjustments throughout the rehabilitation period based on consistent communication among rehabilitation, surgical, and imaging teams to ensure strict patient compliance with restrictions, activities, and timelines to optimize functional outcomes after surgery.