Relationship Between Bone Marrow Lesions on MRI and Cartilage Degeneration in Osteochondral Lesions of the Talar Dome

Inter- and Intra-Observer Variability of the AMADEUS Tool for Osteochondral Lesions of the Talus

BACKGROUND

Managing osteochondral cartilage defects (OCDs) of the talus is a common daily challenge in orthopaedics as they predispose patients to further cartilage damage and progression to osteoarthritis. Therefore, the implementation of a reliable tool to quantify the amount of cartilage damage that is present is of the essence.

METHODS

We retrospectively identified 15 adult patients diagnosed with uncontained OCDs of the talus measuring <150 mm2, which were treated arthroscopically with bone marrow stimulation. Five independent assessors evaluated the pre-operative MRI scans with the AMADEUS scoring system (i.e., MR-based pre-operative assessment system) and the intra-/inter-observer variability was then calculated by means of the intraclass correlation coefficients (ICC) and Kappa (κ) statistics, respectively. In addition, the correlation between the mean AMADEUS scores and pre-operative self-reported outcomes as measured by the Manchester-Oxford foot questionnaire (MOxFQ) was assessed.

RESULTS

The mean ICC and the κ statistic were 0.82 (95% CI [0.71, 0.94]) and 0.42 (95% CI [0.25, 0.59]). The Pearson correlation coefficient was found to be r = -0.618 (p = 0.014).

CONCLUSIONS

The AMADEUS tool, which was originally designed to quantify knee osteochondral defect severity prior to cartilage repair surgery, demonstrated good reliability and moderate inter-observer variability for small OCDs of the talar shoulder. Given the strong negative correlation between the AMADEUS tool and pre-operative clinical scores, this tool could be implemented in clinical practise to reliably quantify the extent of the osteochondral defects of the talus.

Hounsfield Unit values on the subchondral bone are related to clinical outcomes in bone marrow stimulation for osteochondral lesions of the talus

BACKGROUND

Poor clinical outcomes in bone marrow stimulation (BMS) for the osteochondral lesion of the talus (OLT) are caused by subchondral bone deterioration. It is reported that microfracture induces endochondral ossification in the subchondral bone, which may affect the subchondral bone condition after BMS. This study analyzed osteosclerotic patterns of the bed in OLTs on computed tomography (CT) images and the relationship between the subchondral bone condition and clinical outcomes of BMS.

METHODS

Sixty-nine ankles in 61 patients with OLT were included. Hounsfield unit (HU) on the bed of OLTs was measured on CT images and the pattern of osteosclerosis or absorption in the bed was analyzed. In these patients, 25 ankles in 24 patients underwent BMS. They were divided into 2 groups according to the presence of bone marrow edema (BME) one year after surgery, and clinical outcomes were compared.

RESULTS

HUs in the anterior region were significantly higher than those of other areas. In patients with BMS, the JSSF scale for BME positive group (88.0 ± 7.7 points) was significantly lower than that for BME negative group (95.0 ± 6.1 points) (p < 0.05) at the final follow-up. On preoperative CT images, HU values of the central region in the BME-positive group were significantly lower than those in the BME-negative group (p < 0.05).

CONCLUSION

Osteosclerotic changes in the anterior part of the bed were frequently observed, and BMS for the area with low HU values decreased clinical outcomes. BMS should be performed with attention to subchondral bone condition to obtain good clinical outcomes.

LEVEL OF EVIDENCE

4, case series.

Osteochondral Lesion of the Talus: Quality of Life, Lesion Site, and Lesion Size

Osteochondral lesions of the talus (OLTs) are the lesions that affect the articular cartilage and the subchondral bone of the talus. Symptoms develop between 6 and 12 months after the index trauma and are associated with degradation of quality of life. Two-thirds of the lesions (73%) are located on the medial part of the talus, 28% of the lesions are posteromedial, and 31% of the lesions are centromedial. Currently, OLT of up to 100 mm2 can behave in a more indolent condition, and above that area, the defect tends to transmit more shearing forces to adjacent cartilage and is more symptomatic.

Osteochondral Lesions of the Talus: The Questions We Would Like Answered

Osteochondral lesions of the talus is common pathology that foot and ankle surgeons evaluate and treat. There is a variety of treatment modalities at the surgeon's disposal to repair these lesions, which include both open and arthroscopic surgical techniques. Although both open and arthroscopic techniques have a good success rate, there are still many debates and questions that surround this pathology. The goal of this article is to discuss some of the common questions that we ask ourselves and other surgeons.

SPECT/CT imaging features of cystic degeneration of the talus and their relation to pathological findings

Background

Osteochondral lesions of the talus (OLTs) are a common orthopedic condition. The image presentation is very similar to that of ischemic necrosis of the talus complicated by a talar neck fracture, but the two are very different lesions. When abnormalities in bone density (or signal) of the talar body (apex of the fornix) with concomitant bone defects and cystic changes are found on X-ray, computed tomography (CT), or magnetic resonance imaging, it is important to accurately determine the nature of the lesion and make a correct diagnosis for the treatment and prognosis of the patient. The purpose of this study was to explore the imaging features of three-phase single-photon emission computed tomography (SPECT)/CT images of cystic lesions of the talus.

Methods

A total of 189 patients with chronic pain in the ankle joint suspected to be caused by cystic degeneration of the talus were enrolled. All patients underwent 99mTc-methyl diphosphonate (99mTc-MDP) three-phase SPECT/CT bone imaging and delayed scans in our hospital. The location, range of involvement, classification, CT value, and radioactivity uptake of the sclerotic areas of cystic lesions on the talus, and the continuity of the articular surface, were recorded. All recorded parameters were analyzed in comparison with pathological results.

Results

Eighty-three percent (157/189) of the talar cysts were located on the medial fornix, largely involving the anterior middle part (43.27%), with larger cysts involving the posterior part (9.6%). Sixty-three percent (119/189) of the patients had type I lesions and 37% (70/189) had type II lesions. The articular surface of the medial dome of the talus was intact in all patients, but the subchondral bony articular surface was rough in 88% (166/189) of patients. The coincidence rate for the location, type, and range of involvement of cystic lesions with the pathological results was 87.83% (166/189). The mean CT value of the cystic lesions was 45 ± 15 HU (30–60 HU). The percentages of pathological chondrogenesis in high CT value ≥ 50 HU (19/70) and low CT value < 50 HU (51/70) groups were 89.47% (17/19) and 29.14% (15/51) (χ² = 20.12, p < 0.001), respectively. The target/background ratio (T/B ratio) of the radioactivity-uptake area of the talus vault was 2.0 ± 0.5 (1.5–2.5). The percentages of pathological new trabecular bone in those with a T/B ratio ≥ 2.0 (157/189) and T/B ratio < 2.0 (32/189) were 82.80% (130/157) and 25.00% (8/32; χ² = 45.08, p < 0.001), respectively.

Conclusions

Three-phase bone imaging could identify damage of the talus caused by cystic degeneration, while delayed SPECT/CT images showed advantages for displaying bone microstructure, blood supplement, and bone metabolism when examining the location, range of involvement, classification, and repair of cystic lesions of the talus.

Surgical Treatment of Talus OCL: Mid- to Long-Term Clinical Outcome With Detailed Analyses of Return to Sport

Talus osteochondral lesions are a commonly underdiagnosed problem in young athletes. Talus osteochondral lesions surgical algorithm remains controversial. Current metrics suggest that conventional treatment of osteochondral lesions of the talus is promising; yet return to sport is poorly studied. Fifty-seven patients following talus osteochondral lesion surgical intervention were included in this study. About 63.1% were female with mean age 37.1 years, mean lesion size 10 × 12.5 mm, and mean follow-up 79.9 months postoperatively. Patients were divided into 4 groups by surgery performed: antegrade arthroscopic bone marrow stimulation, retrograde arthroscopic drilling, osteochondral autograft transfer, and allograft cartilage implantation. Outcome metrics include Visual Analog Scale for pain and function, Short Form-12, Foot and Ankle Disability Scale, Tegner, Marx activity scores, Naal Sports inventory, and patient satisfaction. Over 77% of patients were satisfied with surgical intervention. Each intervention significantly decreased pain and increased function, except retrograde drilling. All interventions trended toward decreased Tegner score; only antegrade drilling showed significant decrease. Based on Naal's sports inventory, 85.7% of surgically treated patients reported participating in sport activities, on average 3 times/week and 50.6 minutes/session. Traditionally, talus osteochondral lesions present a difficult problem that is marred by unsatisfactory nonoperative outcomes in typically active patients. As our surgical understanding has evolved, we've continued to improve on outcomes. Our patients demonstrated 77.2% overall satisfaction rate, a statistically significant improvement in pain and function, at an average follow-up of 79.9 months postoperatively, and a high rate of return to sport with little difference between surgical interventions.

Identification of Traumatic Bone Marrow Oedema: The Pearls and Pitfalls of Dual-Energy CT (DECT)

Dual-energy computed tomography (DECT) has been reported to successfully identify bone marrow oedema (BME) in various traumatic settings. DECT has multiple strengths, including the availability of both a 3D view of the anatomical area studied and of high-resolution dual energy specific maps super-imposed onto conventional grayscale morphological images. Windowing can be used to enhance the visualization of BME by increasing the level of the super-imposed images. Conversely, by decreasing the level of the super-imposition of color-coded images, it is possible to progressively enhance the visualization of fine anatomical details, which is useful for diagnosing associated imaging findings. Importantly, bone sclerosis may represent an important pitfall for DECT, potentially generating both false positive and false negative findings by locally altering CT numbers. The aim of this paper was to evaluate the strengths and limitations of DECT in accurately detecting traumatic BME, by considering practical approaches to imaging at several anatomical sites.

Identification of Non-Traumatic Bone Marrow Oedema: The Pearls and Pitfalls of Dual-Energy CT (DECT)

Dual-energy computed tomography (DECT) is an imaging technique widely used in traumatic settings to diagnose bone marrow oedema (BME). This paper describes the role of DECT in diagnosing BME in non-traumatic settings by evaluating its reliability in analyzing some of the most common painful syndromes. In particular, with an illustrative approach, the paper describes the possible use of DECT for the evaluation of osteochondral lesions of the knee and of the ankle, avascular necrosis of the hip, non-traumatic stress fractures, and other inflammatory and infectious disorders of the bones.

Surgical treatment for insertional Achilles tendinopathy and retrocalcaneal bursitis: more than 1 year of follow-up

OBJECTIVE

To analyse the imaging changes in bone marrow oedema of the calcaneal prominence, retrocalcaneal bursa and degenerative Achilles tendon after the surgical treatment of insertional Achilles tendinopathy (IAT).

METHODS

This retrospective study analysed patients with IAT and retrocalcaneal bursitis that were diagnosed based on their symptoms and radiographic and magnetic resonance imaging (MRI) examinations. For patients that had received 3 months of conservative treatment but still presented with symptoms, arthroscopic debridement of the retrocalcaneal bursa and resection of calcaneal prominence were undertaken. Patients with degeneration of the Achilles tendon underwent debridement of Achilles tendon calcification with an open incision. The last follow-up included radiographic and MRI imaging, Visual Analogue Scale (VAS) pain scores and American Orthopedic Foot and Ankle Society (AOFAS)-Ankle and Hindfoot scores.

RESULTS

Thirty patients were included (mean ± SD follow-up, 3.1 ± 0.5 years). The VAS pain and AOFAS-Ankle and Hindfoot scores were significantly improved after surgery. MRI showed that bone marrow oedema of the calcaneal prominence and the retrocalcaneal bursa was significantly reduced compared with preoperative values. There was no significant change in the high signal area of the IAT.

CONCLUSION

Surgical treatment of IAT and retrocalcaneal bursitis effectively alleviated local pain and restored function.

Identification of bone marrow edema around the ankle joint in non-traumatic patients: Diagnostic accuracy of dual-energy computed tomography

OBJECTIVES

To evaluate the diagnostic accuracy of DECT in the identification of BME of the ankle in non-traumatic patients.

METHODS

This prospective institutional review board approved study included 40 consecutive patients (21 males and 19 females, mean age 56.8 years, SD = 11.37) that were examined using DECT and MRI in the period between April 2019 and January 2020. Two radiologists (7 and 16 years of experience) evaluated the presence of BME on DECT mages. Diagnostic accuracy values for diagnosing BME on a per-patient and on a per-partition basis analysis were calculated for DECT images by two readers (R1 and R2, with 16 and 7 years of experience, respectively), using MRI as a gold-standard for diagnosis. Inter-observer agreements were calculated with k-statistics. A p-value of <0.05 was considered as statistically significant.

RESULTS

MRI depicted BME in 29/40 patients (72.50%) and in 43/240 partitions (17.91%). The consensus reading by R1 and R2 of DECT images allowed us to achieve 89.7% sensitivity (26/29 patients) and 81.8% specificity (9/11 patients). Regarding the partitions-basis analysis, BME was depicted by DECT in 39/43 partitions (90.69% sensitivity), and ruled out in 189/197 partitions (95.93% specificity). Sensitivity and specificity for the most involved partitions (talar dome) were both 95%. The inter-observer agreement for patients' analysis was substantial (k = 0.697), whereas for the partitions' analysis, it ranged from substantial (k = 0.724) to near perfect (k = 0.950).

CONCLUSIONS

DECT can accurately diagnose BME of the ankle in a cohort of non-traumatic patients.

Ligament stabilization improved clinical and radiographic outcomes for individuals with chronic ankle instability and medial ankle osteoarthritis

PURPOSE

Chronic ankle instability with a long symptom duration is often accompanied by medial compartment ankle osteoarthritis (OA). However, the outcomes of individuals after ligament stabilization have rarely been reported. The radiographic and clinical outcomes after ligament stabilization in individuals with chronic ankle instability and medial compartment OA were investigated.

METHODS

The study investigated 27 ankles with chronic ankle instability and medial compartment OA that underwent lateral ankle ligament reconstruction from 2007 to 2015 with a follow-up period of at least 1 year. Ligament stabilization was performed via either the modified Broström procedure (MBP) or lateral ankle reconstruction (LAR) using semitendinosus tendon allografts.

RESULTS

The median instability duration was 60 (range 12-480) months, and the median follow-up period was 39 (range 12-108) months. The preoperative Takakura ankle OA stage was predominantly stage I (20 patients (74.1%)), followed by stage II (five patients (18.5%)). Ankle MRI (20 ankles) revealed medial cartilage denudation in three cases (15%), cartilage thinning in nine cases (45%), osteophyte formation in ten cases (50%), and loose body formation in six cases (30%). According to the arthroscopic results, the modified Outerbridge grade was two in nine cases and four in ten cases, so these grades were the most common (37.5% and 41.7%, respectively). The MBP was performed in 14 patients, and LAR was performed in 13 patients (52% and 48%, respectively); the bone marrow stimulation procedure was performed in 15 patients (55%). The visual analogue scale score decreased from 6.0 (SD 1.6) preoperatively to 1.8 (SD 1.6) postoperatively (p = 0.000). The American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score improved from 61.9 (SD 14.2) to 89.7 (SD 6.2), and the Karlsson-Peterson score improved from 54.7 (SD 13.9) to 88.3 (SD 9.0) (p = 0.000). There were no serious complications, and all patients were satisfied.

CONCLUSIONS

Ligament stabilization with arthroscopic procedures for individuals with chronic ankle instability and medial ankle OA yielded significant functional outcomes with high patient satisfaction, even without radiographic improvement.

LEVEL OF EVIDENCE

IV.

Both Magnetic Resonance Imaging and Computed Tomography Are Reliable and Valid in Evaluating Cystic Osteochondral Lesions of the Talus

Background

Compared with computed tomography (CT), magnetic resonance imaging (MRI) might overestimate the condition of osteochondral lesions of the talus (OLTs) owing to subchondral bone marrow edema and the overlying cartilage defect. However, no study has compared MRI and CT directly in evaluating OLTs with subchondral cysts.

Purpose

To compare the reliability and validity of MRI and CT in evaluating OLTs with subchondral cysts.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

An institutional radiology database was queried for inpatients diagnosed with OLTs with subchondral cysts who had undergone surgical treatment between May 2015 and October 2019. A total of 48 patients met the inclusion criteria. Based on our measurement method, 2 experienced observers who were blinded to the study independently measured the length, width, and depth of the cysts using MRI and CT. The classification of cystic lesions was also performed based on MRI and CT findings.

Results

Interobserver reliability was almost perfect, with intraclass correlation coefficients (ICCs) ranging from 0.935 to 0.999. ICCs for intraobserver reliability ranged from 0.944 to 0.976. The mean size of cysts measured on MRI (length, 13.38 ± 4.23 mm; width, 9.28 ± 2.28 mm; depth, 11.54 ± 3.69 mm) was not significantly different to that evaluated on CT (length, 13.40 ± 4.08 mm; width, 9.25 ± 2.34 mm; depth, 11.32 ± 3.54 mm). The size of subchondral cysts was precisely estimated on both MRI and CT. The MRI classification and CT classification revealed almost perfect agreement (kappa = 0.831).

Conclusion

With our measurement method, both MRI and CT were deemed to be reliable and valid in evaluating the size of subchondral cysts of OLTs, and the MRI classification was well-correlated with the CT classification. The presented measurement method and classification systems could provide more accurate information before surgery.

Relationship of T2 Value of High-signal Line on MRI to the Fragment in Osteochondral Lesion of the Talus

BACKGROUND

Magnetic resonance imaging (MRI) is useful for evaluating the stability of an osteochondral lesion of the talus (OLT). A T2 high-signal line between the fragment and its bed on MRI is known as a reliable indicator of an unstable lesion. However, the lesion exhibits various conditions even if a T2 high-signal line is observed. The purpose of this study was to evaluate the relationship between the T2 value of a high-signal line and the condition of the area between the fragment and its bed in OLT.

METHODS

T2 values of the T2 high-signal line and those of joint fluid were measured from preoperative MRI images in 46 ankles with OLT and the T2 ratio (high-signal line / joint fluid) was calculated. The relationship between the T2 ratio and CT, arthroscopic, and histologic findings was examined.

RESULTS

The mean T2 ratio was 0.48. T2 ratios of cystic lesions (0.62) or bone absorption (0.67) in the bed were significantly higher than those without a cyst (0.40) or no absorption (0.40). The T2 ratio of an unstable lesion (0.51) was significantly lower than that of a stable lesion (0.29). In histologic findings, there were 2 separate patterns: chondral and subchondral bone separations. The T2 ratio of the chondral separation (0.60) was significantly higher than that of bone separation (0.48).

CONCLUSION

This study showed that the T2 ratio on a high-signal line was a predictor of stability, cyst, and bone absorption in OLT.

LEVEL OF EVIDENCE

Level III, comparative series.

Patient-Reported Outcomes After Structural Autograft for Large or Cystic Talar Dome Osteochondral Lesions

BACKGROUND

While smaller talar dome osteochondral lesions (OCLs) are successfully treated with bone marrow stimulation techniques, the optimal treatment for large or cystic OCLs remains controversial. This study tested the hypothesis that transferring structural autograft bone from the distal tibia to the talus for large or cystic OCLs improves pain and function.

METHODS

Thirty-two patients with large or cystic OCLs underwent structural bone grafting from the ipsilateral distal tibia to the talar dome. Patients were assessed with subjective patient-centered tools and objective clinical outcomes. Average age was 48.6 ± 14.9 years, and average follow-up was 19.5 ± 13.3 months. Average lesion area was 86.2 ± 23.5 mm², and average depth was 8.4 ± 3.0mm.

RESULTS

At final follow-up, improvement compared to preoperative scores was seen in American Orthopaedic Foot & Ankle Society (65.4 ± 21.2 to 86.9 ± 15.0, P < .05), Foot Function Index (48.9 ± 20.8 to 21.1 ± 18.9, P < .05), visual analog scale for pain (4.7 ± 3.0 to 1.4 ± 1.5, P < .05), and Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (40.4 ± 5.4 to 45.5 ± 7.4, P < .05) scores. There was no improvement in PROMIS pain interference (54.7 ± 18.1 to 52.4 ± 7.3, P > .05). Satisfaction with surgery was 8.4 ± 1.3/10, and 96% of patients would have the procedure again. Ninety-four percent of patients returned to work and/or play. One patient had a deep vein thrombosis 6 weeks postoperatively, and 1 patient underwent ankle fusion at 18 months postoperatively.

CONCLUSION

This study demonstrates that structural bone graft harvested from the distal tibia transferred to the talus was a safe and effective treatment for large and cystic OCLs. Outcomes compare favorably to other described techniques for treatment of these injuries.

LEVEL OF EVIDENCE

Level IV, case series.

Retrograde Drilling for Osteochondral Lesion of the Talus in Juvenile Patients

Background:

Retrograde drilling (RD) is generally used for treating osteochondral lesion of the talus (OLT) with a stable osteochondral fragment and nearly normal articular cartilage surface. Previous studies that included participants of various ages have reported good clinical results. This study aimed to clarify the clinical outcomes of RD for OLT in juvenile patients whose bone-forming ability and physical activity might affect the healing process.

Methods:

This retrospective study included 8 juvenile patients who underwent RD for OLT (5 boys and 3 girls, mean age 14.9 years, mean follow-up 2 years, 7 medial and 1 central lesion). American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score and ankle activity score were evaluated, and arthroscopic findings were graded according to the International Cartilage Research Society (ICRS) classification system. The condition of the underlying bone was assessed on preoperative computed tomographic images. The stability, incorporation, and subsidence of the osteochondral fragment, articular surface congruity, and the area of the bone marrow lesion (BML) were evaluated using magnetic resonance imaging (MRI).

Results:

AOFAS ankle-hindfoot score and ankle activity score significantly improved postoperatively. Arthroscopically, the lesions were classified as ICRS grade 0 or 1. Bone sclerosis or multiple small cysts of the underlying bone were observed in all patients. MRI demonstrated no signs of osteochondral fragment instability or subsidence, good or fair fragment incorporation, good articular surface congruity, or slight irregularity. The postoperative BML was reduced; however, these BMLs were still detectable at 1 year after surgery.

Conclusion:

Our data suggested that RD is an option for treating juvenile patients with OLT refractory to nonoperative treatment at short-term follow-up. Although bone sclerosis or multiple small cysts were identified in the underlying bone preoperatively and the BML under the osteochondral fragment remained postoperatively, clinical status such as pain and physical activity level were improved by RD.

Level of Evidence:

Level IV, retrospective case series.

Clinical Results of Bioabsorbable Pin Fixation Relative to the Bone Condition for Osteochondral Lesion of the Talus

BACKGROUND

Fixation of an osteochondral lesion of the talus (OLT) can restore the natural congruency of the joint surface with hyaline cartilage. In this procedure, the bone condition of the osteochondral fragment is important for stabilizing the lesion, and it may affect clinical outcomes. The aim of this study was to explore the influence of the fragment's bone condition on clinical outcomes.

METHODS

Eighteen ankles in 17 patients with a mean age of 20.1 years, which had undergone fixation of an OLT using bioabsorbable pins, were included. Based on the fragment's bone condition on preoperative computed tomography scans, ankles were divided into 3 groups: normal, segmentation, and absorption. The American Orthopaedic Foot & Ankle Society (AOFAS) scale and magnetic resonance imaging (MRI) findings were evaluated both pre- and postoperatively. Second-look arthroscopic findings were evaluated in 15 ankles and were compared with biopsy specimens from the initial surgery.

RESULTS

The AOFAS scale significantly improved at the final follow-up in all groups with no significant differences among the 3 groups. MRI at 1 year showed good bone incorporation and a congruent cartilage surface in all groups, but the bone marrow lesion in the absorption group was significantly larger than that in the other groups. In second-look arthroscopy, all ankles showed stable and near-normal cartilage. There was no significant correlation between arthroscopic and histological findings.

CONCLUSION

We found that fixation can be considered when there is a good cartilage surface on a large OLT, even if bone absorption in the fragment exists.

LEVEL OF EVIDENCE

Level III, comparative study.

Prevalence of bone marrow edema in a study population with foot and/or ankle pain

Bone marrow edema (BME) is an imaging diagnosis defined by an abnormal accumulation of intraosseous interstitial fluid within a bone on magnetic resonance imaging (MRI) investigation. The aim of this study was to determine the prevalence of BME in patients with foot and/or ankle pain studied using MRI. This was a retrospective observational work on patient cases and controls studied through MRI of the foot and/or ankle at our Foot and Ankle Unit (FAU). An analytical statistical analysis and a multivariate analysis were performed to eliminate possible confounding factors. 1950 foot and/or ankle MRI cases were reviewed, of which 451 presented bone edema (23% prevalence). The average patient age was 51.8 (range, 7-87); the talus bone was most frequently affected: post-traumatic in 43.5% of cases, degenerative in 34.7% and there was no specific cause identified in 6.3% (these cases were termed 'idiopathic'). With regards to risk factors, in the case of gender, the odds ratio (OR) of men suffering bone oedema was 1.5 times higher than that of women (P = 0.003); for immunosuppression the OR was 3.4 times higher (P = 0.001); while among those with a smoking habit it was 0.59 (P = 0.001), meaning that after ruling smoking out as a possible confounding factor, it was, in fact, revealed to be a protective factor. The prevalence of bone edema in MRI in patients with foot and/or ankle pain was 23%. The average patient was male, aged approximately 50, with traumatic or degenerative origin talus bone oedema. Level of Evidence: Level IV, revision observational study.

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.

MRI Tracking of the Effect of Bioabsorbable Pins on Bone Marrow Edema After Fixation of the Osteochondral Fragment in the Talus

BACKGROUND:

Large osteochondral lesions of the talus (OLT) with good articular cartilage can be fixed by using bioabsorbable pins. These pins have various advantages but they can have adverse effects such as foreign body inflammation. This negative impact of pins on subchondral bone can be seen as bone marrow edema (BME) on magnetic resonance imaging (MRI). The purpose of this study was to investigate the course of change in BME on MRI, including osteolytic change around pins in OLT treated with pin fixation.

METHODS:

This study comprised 13 ankles in 12 patients, who underwent surgeries to fix an OLT using poly-l-lactide acid pins. MRIs were taken at preoperative, 3, 6, and 12 months after surgery. The area of BME was measured at each time point, and osteolytic change around pins was evaluated. Moreover, pin insertion angle was measured.

RESULTS:

BME significantly decreased from preoperative to 6 and 12 months. At 1 year, 28.1% of pins exhibited osteolytic change around them. Pin insertion angle was significantly lower in those with osteolytic change than those with no osteolytic change. At 3 and 6 months and 1 year postoperatively, BME with osteolytic change was significantly greater than those patients with no osteolytic change. The American Orthopaedic Foot & Ankle Society score significantly improved from preoperative (76.6±3.4 points) to 1 year after surgery (98.5±3.8 points).

CONCLUSION:

A shallow pin insertion angle was associated with osteolytic change around pins and persistence of BME on MRI, although excellent results were obtained at 1 year after surgery.

LEVEL OF EVIDENCE:

Level III, retrospective comparative series.