Subchondral Bone Degradation After Microfracture for Osteochondral Lesions of the Talus: An MRI Analysis

Arthroscopic microfracture vs. arthroscopic autologous matrix-induced chondrogenesis for the treatment of articular cartilage defects of the talus

PURPOSE

Microfracture is an established method to treat osteochondral defects of the talus. The value of the addition of an acellular matrix is still under debate. This study compared the results of arthroscopic microfracture vs. arthroscopic autologous matrix-induced chondrogenesis using a collagen I/III matrix (AMIC) in the management of articular cartilage defects of the talus.

METHODS

Patients with a minimum follow-up of 5 years after arthroscopic management for an articular cartilage defect of the talus with either microfracture alone or an additional acellular matrix were matched according to age, sex and BMI. The Hannover Scoring System for the ankle (HSS) and a Visual analog scale (VAS) for pain, function and satisfaction were used to evaluate the clinical outcome. Postoperative MRI was used to assess cartilage repair tissue based on the degree of defect repair and filling of the defect, integration to border zone, surface of the repair tissue, structure of the repair tissue, and subchondral bone alterations.

RESULTS

Thirty-two patients (16 microfracture, 16 AMIC) were included. No significant between-group differences were observed in demographic data and preoperative score values. Both groups showed statistically significant improvement when comparing the pre- and postoperative score values. No statistically significant differences were identified between the median values of the groups with the HSS (microfracture: 82 (range 71-96) points; AMIC 88 (range 40-98) points). Accordingly, no significant differences were observed for the VAS pain (microfracture: 0.95 (range 0-3.8); AMIC: 1.0 (range 0-8.5)), VAS function (microfracture: 8.4 (range 3.5-10); AMIC: 9.0 (range 1.5-10)) and VAS satisfaction (microfracture: 8.9 (range 2.8-10); AMIC: 9.45 (range 1.5-10)). MRI showed regeneration of tissue in the treated area without differences between the two groups.

CONCLUSION

Good clinical results were observed for arthroscopic microfracture with or without an additional acellular collagen I/III matrix in the treatment for articular cartilage defects of the talus. It appears that for defects as treated in this study, it is not worthwhile adding the collagen I/III matrix to the microfractures.

LEVEL OF EVIDENCE

III.

Beyond Cartilage Repair: The Role of the Osteochondral Unit in Joint Health and Disease

Once believed to be limited to articular cartilage, osteoarthritis is now considered to be an organ disease of the “whole joint.” Damage to the articular surface can lead to, be caused by, or occur in parallel with, damage to other tissues in the joint. The relationship between cartilage and the underlying subchondral bone has particular importance when assessing joint health and determining treatment strategies. The articular cartilage is anchored to the subchondral bone through an interface of calcified cartilage, which as a whole makes up the osteochondral unit. This unit functions primarily by transferring load-bearing weight over the joint to allow for normal joint articulation and movement. Unfortunately, irreversible damage and degeneration of the osteochondral unit can severely limit joint function. Our understanding of joint pain, the primary complaint of patients, is poorly understood and past efforts toward structural cartilage restoration have often not been associated with a reduction in pain. Continued research focusing on the contribution of subchondral bone and restoration of the entire osteochondral unit are therefore needed, with the hope that this will lead to curative, and not merely palliative, treatment options. The purpose of this narrative review is to investigate the role of the osteochondral unit in joint health and disease. Topics of discussion include the crosstalk between cartilage and bone, the efficacy of diagnostic procedures, the origins of joint pain, current and emerging treatment paradigms, and suitable preclinical animal models for safety and efficacy assessment of novel osteochondral therapies. The goal of the review is to facilitate an appreciation of the important role played by the subchondral bone in joint pain and why the osteochondral unit as a whole should be considered in many cases of joint restoration strategies.

Identification of bone marrow edema of the ankle: diagnostic accuracy of dual-energy CT in comparison with MRI

OBJECTIVE

To evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) to identify bone marrow edema (BME) of the ankle.

METHODS

This prospective institutional review board approved study included 40 consecutive patients (29 males and 11 females; mean age of 32.3 years) studied with DECT (80 kV and tin filter 150 kV) and MRI within 10 days. DECT data were post-processed for generating non-calcium images of the ankle. Two radiologists evaluated the presence of BME on color-coded maps. Diagnostic accuracy values for diagnosing BME were calculated for DECT maps (qualitative assessment) and for CT numbers (quantitative assessment) by using receiver operator curves and area under the curve (AUC), using MRI as the gold standard. Interobserver and intraobserver agreements were calculated with k-statistics. A p < 0.05 was considered statistically significant.

RESULTS

DECT depicted BME in 23/25 patients (92.0%). The sensitivity, specificity, PPV and NPV, and accuracy achieved by evaluating the DECT images were 92.0, 86.6, 92.0, 84.6, and 90.0%, for reader 1 and 88.0, 86.6, 91.6, 78.6, and 87.5, for reader 2, respectively. The interobserver and intraobsever agreements were near perfect (k = 0.87 and k = 0.83, respectively). DECT numbers were significantly different between positive (mean - 12.6 ± 29.6 HU) and negative cases (mean - 64.2 ± 34.5 HU) with a p value < 0.001. By using - 20HU cutoff to identify BME (AUC of 0.896.), the sensitivity, specificity, PPV and NPV, and accuracy of the quantitative analysis were 88.0, 92.6, 95.7, 92.6, and 87.5%, respectively.

CONCLUSION

DECT represents an accurate imaging tool for demonstration of BME of the ankle when compared to MRI.

Decreased Graft Thickness Is Associated With Subchondral Cyst Formation After Osteochondral Allograft Transplantation in the Knee

BACKGROUND

Subchondral changes, specifically cyst formation, are a known finding after osteochondral allograft (OCA) transplantation.

PURPOSE/HYPOTHESIS

The purpose was to determine potential predictive associations between preoperative patient characteristics or OCA morphology and postoperative OCA appearance as assessed by the osteochondral allograft magnetic resonance imaging scoring system (OCAMRISS) at 6-month follow-up. It was hypothesized that preoperative patient factors or OCA morphology is associated with postoperative OCAMRISS scores.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

This study evaluated 74 OCAs that were implanted in the femoral condyles of 63 patients for the treatment of symptomatic osteochondral defects in the knee. Postoperative magnetic resonance imaging was obtained at a mean ± SD follow-up of 5.5 ± 1.0 months. A musculoskeletal radiologist scored all grafts according to the OCAMRISS. Point biserial correlation, Mann-Whitney U test, Fisher exact test, and chi-square test were used to distinguish associations between OCAMRISS subscales and age, sex, smoker status, body mass index, previous surgery, concomitant surgery, bone marrow augmentation, graft location, graft size, and bony graft thickness.

RESULTS

OCA bony thickness showed significant correlation with cystic changes at the graft-host junction (P = .019). Grafts with cystic formation were significantly thinner than grafts without cystic changes (P = .008). The odds ratio for grafts with <5-mm bony thickness demonstrating cystic changes was 4.9 (95% CI, 1.5-16.1; P = .009). Bony graft thickness was not associated with graft integration, but 40% of grafts with a bony thickness >9 mm presented with a residual osseous cleft, as opposed to 11.3% of thinner grafts (P = .1). The augmentation with bone marrow aspirate did not affect osseous graft integration or subchondral cystic formation (P = .375 and P = .458, respectively).

CONCLUSION

Osteochondral allograft thickness is associated with subchondral cyst formation at short-term follow-up. Thin grafts demonstrate a substantially increased risk of developing subchondral cysts at the graft-host junction after OCA transplantation. Conversely, thicker grafts may negatively affect osseous graft integration. Hence, surgeons should be aware of the potential pitfalls of transplanting thin or thick grafts regarding cystic formation and delay of osseous integration after cartilage resurfacing.

Concentrated Bone Marrow Aspirate May Decrease Postoperative Cyst Occurrence Rate in Autologous Osteochondral Transplantation for Osteochondral Lesions of the Talus

PURPOSE

To clarify if the use of concentrated bone marrow aspirate (CBMA) would affect both postoperative functional outcomes and magnetic resonance imaging (MRI) outcomes compared with those of autologous osteochondral transplantation (AOT) alone; in addition, to assess the efficacy of CBMA reducing the presence of postoperative cyst formation following AOT in the treatment of osteochondral lesions of the talus.

METHODS

Fifty-four (92%) of 59 eligible patients who underwent AOT between 2004 and 2008 were retrospectively assessed at a minimum of 5-year follow-up. Twenty-eight patients were treated with AOT and CBMA (AOT/CBMA group) and 26 patients were treated with AOT alone (AOT-alone group). Clinical outcomes were evaluated using the Foot and Ankle Outcome Scores (FAOS) and Short-Form 12 (SF-12) preoperatively and at final follow-up. Postoperative MRI was evaluated with the modified Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring system. Cyst formation was also evaluated on postoperative MRI.

RESULTS

The mean FAOS and SF-12 significantly improved in both the AOT/CBMA and AOT-alone groups, but there were no statistical differences between groups in FAOS (80.5 vs 75.5, P = .225) and SF-12 (71.1 vs 69.6, P = .756) at final follow-up. Additionally, there was no difference in the mean MOCART score (80.4 vs 84.3, P = .484); however, AOT/CBMA did result in a statistically lower rate of cyst formation (46.4% vs 76.9%, P = .022). No significant differences were found in the mean postoperative FAOS and SF-12 between patients with and without cysts postoperatively.

CONCLUSIONS

CBMA reduced postoperative cyst occurrence rate in patients treated with AOT; however, CBMA did not result in significant differences in medium term functional outcomes and MOCART score in patients who underwent AOT.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Good clinical and functional outcomes at mid-term following autologous osteochondral transplantation for osteochondral lesions of the talus

PURPOSE

Autologous osteochondral transplantation is an established treatment for large-sized osteochondral lesions of the talus (OLT) with excellent short term outcomes. However, few studies assess the outcomes of autologous osteochondral transplantation at mid-term follow-up. The purpose of the current systematic review was to evaluate the clinical outcomes of the autologous osteochondral transplantation procedure in the treatment of OLT at mid-term and long-term follow-up.

METHODS

A systematic search of the MEDLINE, EMBASE and Cochrane Library databases was performed in October 2017 based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Included studies were evaluated with regard to level of evidence (LOE) and quality of evidence (QOE) using the Coleman Methodology Score. Clinical outcomes, and complications were also evaluated.

RESULTS

Eleven studies, with 500 ankles were included at a mean 62.8 months follow-up. Seven studies used the American Orthopaedic Foot and Ankle Society (AOFAS) score. The weighted mean preoperative AOFAS score was 55.1 ± 6.1, and the postoperative score was 86.2 ± 4.5, with 87.4% of patients (132 of 151) being reported as excellent or good results. In total, 53 of the 500 patients (10.6%) had complications. The most common complication was donor site morbidity with 18 patients (3.6%) at final follow-up. Thirty-one patients (6.2%) underwent reoperations, and 5 ankles (1.0%) were regarded as failed autologous osteochondral transplantation.

CONCLUSION

The current systematic review demonstrated that good clinical and functional outcomes can be expected following autologous osteochondral transplantation for the treatment of OLT, with a low failure rate. The results from this study show patients can be reasonably counselled to expect good clinical outcomes in the mid-term. MRI and radiographs showed restoration of articular surface as well as a minimal presence of osteoarthritis at mid-term follow-up. However, as low level and quality of evidence and the variability of the data may confound the data, further well-designed studies are necessary to determine the effectiveness of autologous osteochondral transplantation in the treatment for OLT.

LEVEL OF EVIDENCE

IV.

The Presence and Degree of Bone Marrow Edema Influence Midterm Clinical Outcomes After Microfracture for Osteochondral Lesions of the Talus

BACKGROUND

Subchondral bone marrow edema (BME) has been associated with articular cartilage loss, with the potential to be a negative prognostic indicator for clinical outcomes after microfracture. However, no single study has investigated the association between BME and clinical outcomes after microfracture for osteochondral lesions of the talus (OLTs) at midterm follow-up.

PURPOSE

To clarify the association between postoperative subchondral BME and clinical outcomes in patients treated with microfracture for OLTs at both short-term and midterm follow-up using a grading system that classified the extent of BME of the talus.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent microfracture between 2008 and 2013 were assessed at 2- and 4-year postoperative follow-up. BME was evaluated using magnetic resonance imaging, and the presence of subchondral BME was determined with fat-suppressed T2-weighted sequences. Clinical outcomes were evaluated using the Foot and Ankle Outcome Score (FAOS). P < .05 was considered to be statistically significant.

RESULTS

Forty-three (83%) of 52 eligible patients were included. No significant differences were found in the FAOS between the BME and no BME groups at 2-year follow-up (83.1 ± 6.5 vs 88.6 ± 8.0, respectively; P = .109), but there was a significant difference at 4-year follow-up (77.5 ± 11.1 vs 84.7 ± 8.4, respectively; P = .041). A significant difference was found among BME grades at 4-year follow-up (grade 0: 84.7 ± 7.4, grade 1: 80.1 ± 10.5, grade 2: 74.0 ± 10.3, and grade 3: 67.5 ± 7.1; P = .035). A post hoc analysis showed significant differences between grades 0 and 2, 0 and 3, and 1 and 3 ( P = .041, .037, and .048, respectively). In addition, at 4-year follow-up, a significant correlation was noted between the FAOS and BME grade ( r = -0.453, P = .003) but not at 2-year follow-up ( r = -0.212, P = .178). Seventy-four percent of patients still had subchondral BME at 4-year follow-up after microfracture for OLTs.

CONCLUSION

Patients with subchondral BME at midterm follow-up after microfracture for OLTs had worse clinical outcomes than those without subchondral BME. In addition, the degree of subchondral BME at midterm follow-up was correlated with clinical outcomes. However, at short-term follow-up, there were no significant differences in clinical outcomes based on both the presence and degree of BME, and no correlation was found between clinical outcomes and the degree of BME. The current study suggests that BME at short-term follow-up is a normal physiological reaction. However, BME at midterm follow-up after microfracture for OLTs may be pathological and is associated with poorer clinical outcomes.