Clinical Outcomes of Talus Bone Marrow Edema: Comparing Plaster Cast, Crutches, and Walking Boot Treatments

Introduction

ISCHEMIC BME:

This includes conditions like osteonecrosis, BME syndrome, osteochondritis dissecans, and complex regional pain syndrome. It occurs in conditions where blood flow to the bone is impaired, resulting in its ischemia.

MECHANICAL BME:

This includes bone contusion (or bone bruise), microfracture, stress-related BME, and stress fractures. These are usually caused by trauma or repetitive stress causing physical alteration and insult to the structure of the bone.

REACTIVE BME:

This includes gonarthritis, osteoarthritis, postoperative BME, and tumor-related BME. It develops as a response to pathology of the joints or bones, surgical procedures involving these regions, or tumors, and represents inflammation or healing.

It is most frequently encountered in trauma and considered a ‘bone bruise’. Conditions are both a result of acute injury and chronic repetitive stress that cause disruption of the trabecular bone within the marrow [2]. BME is quite common in the bone tissues of the foot and ankle following acute ankle injuries [5]. The talus bone is the most commonly affected bone in these injuries [7,8]. There is a lack of studies comparing orthopedic conservative treatments (such as casting, boot immobilization, and non-weight-bearing crutches). This study aimed to evaluate the clinical data obtained from follow-up of acute traumatic BME lesions detected in the talus using MRI after acute ankle injuries and to compare 3 different conservative treatment options. The primary objective was to determine the most appropriate conservative treatment option. Therefore, this study from a single center was conducted between 2015 and 2020 and aimed to compare outcomes from 70 patients diagnosed with traumatic BME of the talus with the use of a plaster cast, crutches, or a walking boot.

Material and Methods

PATIENT SELECTıON:

The study was conducted in accordance with the principles of the Helsinki Declaration and approved by the ethics committee of the local university (09.10.2023-E-22686390-050.99-33161). Prior to obtaining written consent, eligible patients were given both verbal and written information about the study. Clinical trial registration was not performed because the study was retrospective. Between May 2015 and December 2020, a total of 70 patients who had direct radiographs taken after acute ankle inversion injuries, with fractures ruled out but with suspected soft tissue injuries, bone or cartilage tissue damage, underwent MRI investigations and were diagnosed with talus BME were included in the evaluation by 2 different radiologists. Only stage 1 patients according to the Lynch classification were included [4]. It also excluded ligament ruptures, fractures, BME in other bones, and injuries extending into the chondral and subchondral regions from the study. Patients with BME syndrome were also excluded. BME syndrome is characterized by idiopathic pain and swelling within the bone marrow, which is associated with many metabolic disorders like vitamin D deficiency [9,10]. This is quite common among pregnant women during the third trimester. By contrast, our research deals with BME as a consequence of traumatic injuries, and therefore not BME syndrome. To ensure that estimates of traumatic BME would be correctly informed by this study, we excluded patients with metabolic disturbances such as cirrhosis or type IV hyperlipoproteinemia, which are associated with BME syndrome.

IMAGING AND DıAGNOSıS:

An MRI was performed using a 3.0 Tesla Signa Pioneer 97-channel GE USA MRI system with a 17-channel in vivo coil. Images were acquired in sagittal, axial, and coronal planes using T2-weighted and short time inversion recovery (STIR) sequences. The diagnosis of BME in the talus was confirmed using MRI, specifically with T2-weighted and STIR sequences, which are sensitive to the increased interstitial fluid characteristic of BME (Figure 1). MRI was performed at the initial assessment and the results were reviewed by 2 independent radiologists. BME diagnosis was confirmed using T2-weighted and STIR sequences, focusing on signal intensity changes indicative of edema.

PLASTER CAST:

3M Scotch Cast (St. Paul, MN, USA) was used to apply the plaster casts. Over a cast sock, we applied casting padding and an additional 2 layers of rigid plaster. Thus, immobilization of the affected area with a plaster cast prevents further injury and allows healing by reducing movement and pressure on the bone. In the BME cases, a cast was applied to limit weight-bearing and movement of the affected joint, reducing intraosseous pressure, allowing recovery of the bone. Weight-bearing was prevented for 3 weeks by using a plaster cast; after that period, weight-bearing was allowed following tolerance. A plaster cast was applied to restrict weight-bearing for 3 weeks, after which the patients were gradually allowed weight-bearing according to their tolerance.

CRUTCHES:

The crutches (Comfort plus Herdegen Evolution Canadian, Fatih, Istanbul, Turkey) completely offloaded the affected limb to prevent any weight-bearing during the acute phase of recovery. Crutches allowed the patient to maintain mobility while avoiding weight-bearing pressure on the injured bone, which is very important in encouraging healing and reducing further complications. Crutches were used to limit weight-bearing for 3 weeks.

WALKING BOOT: An adjustable walking boot was used, obtained from Medi Protect CAT Walker (Cankaya, Ankara, Turkey). The walking boot provided a balance between immobilization and mobility. It constricted ankle movement to avoid stress on the affected area while allowing weight-bearing to some extent, normally as tolerated by the patient (Figure 2).

GROUP 1 (N: 33):

Plaster cast treatment with total weight-bearing avoidance for 3 weeks, followed by the start of gradual total weight-bearing.

GROUP 2 (N: 21):

Patients used crutches for non-weight-bearing for 3 weeks.

GROUP 3 (N: 16):

Patients were treated using an adjustable walking boot and allowed to bear partial weight.

OUTCOME MEASURES:

AOFAS scores and VAS pain scores were obtained postoperatively. Baseline scores were used to measure and repeated in 8 weeks by each group’s blinded, independent assessors. AOFAS scoring includes items of assessment for pain, functional ability, activity level, walking distance, and joint movements relative to stability and alignment. Pain was measured on a visual analog scale in centimeters along a 10-centimeter-long continuum; the endpoints were labeled 0 (no pain) and 10 (severe pain). These measurements were analyzed as retrospective measurements.

STATISTICAL ANALYSIS:

Data analysis was performed using SPSS version 21.0. Categorical data are expressed as frequency and percentage. Continuous variables are expressed as mean±standard deviation or median with minimum-maximum values, depending on distribution of the data. Then, according to the data distribution, checked by the Kolmogorov-Smirnov test, continuous data were classed into parametric and nonparametric.

The Kruskal-Wallis test collates 3 or more groups across continuous variables. It is a nonparametric distribution. After this, the Dunn test (a post hoc analysis) wwas performed to determine which of the 3 groups differed significantly. For this, the Wilcoxon test was used to measure variables taken before and after treatment on the same patients. In this context, statistical significance throughout this study remained below 0.05.

Results

PATıENT DEMOGRAPHıCS:

We enrolled a total of 70 patients: 33 in Group 1, 21 in Group 2, and 16 in Group 3. The mean age was 34.69±12.05 years. There were 40 (57.1%) males and 30 (42.9%) females.

AOFAS SCORES:

AOFAS pre-treatment values were not significantly different among the 3 groups (P>0.05). However, during the 8-week follow-up, it was clear that there was a statistically significant difference in the AOFAS scores (P=0.002). While comparing the AOFAS post-treatment scores, Group 2 showed significantly higher scores than Group 1 (P=0.001). Between Group 1 and Group 3, no significant difference was observed, since the P value remained greater than 0.05. Also, there was no significant between Group 2 and Group 3 (P>0.05)

VAS SCORES:

The median values of pre- and post-treatment VAS were significantly different among groups (P=0.007. Group 2 had significantly higher values of both pre- and post-treatment VAS compared to Group 1 (P=0.005). There was no significant difference in VAS scores between Group 2 versus Group 3 and Group 1 versus Group 3. Very low post-treatment values of VAS scores in comparison to their pre-treatment values were seen in all 3 groups (P<0.001). Results are depicted in Figure 3.

INTRA-GROUP ANALYSIS:

The intra-group analyses showed that the VAS values significantly decreased after the treatment compared to before treatment in all 3 groups (P<0.001) (Table 1).

Discussion

WHıCH IMAGING TECHNıQUES SHOULD BE APPLIED?:

MRI is the main imaging technique used to diagnose BME [13,14]. T2-weighted images demonstrate increased signal intensity, representing intraosseous edema, hemorrhage, and an inflammatory response.

STIR has the advantage of detecting bone edema and hemorrhage since fat tissue is suppressed [15]. On MRI, signal change allows visualization disruption of the subchondral bone plate. It has been reported that 3.0 Tesla MRI demonstrates more pathology than 1.5 Tesla, particularly cartilage, subchondral bone edema, and suspected OCL [16]. In the current study, 3 Tesla MRI was performed and included patients with no subchondral involvement.

Diagnostic CT may assist in making diagnosis of accompanying subchondral collapses, subchondral fractures, and larger cystic and/or displaced lesions; CT does not have a role in diagnosing BME [3]. However, dual-energy CT with calcium elimination techniques has been shown to demonstrate edema in the bone with quality comparable to MRI [17,18]. Single-photon emission computed tomography (SPECT) has tremendous value in imaging bone edema, osteoblastic activity, and subchondral bone plate. The literature shows that SPECT is better than MRI in diagnosis of disrupted subchondral bone plate [3,19]. Bone scintigraphy is sensitive but lacks specificity. Post-trauma direct radiographs can demonstrate fractures and OCL, but cannot demonstrate BME. It is important to note that ligament injuries can accompany avulsion fractures that suggest BME [3,20].

MRI allows evaluation of cartilage injuries, and ligaments and tendon structures. SPECT, scintigraphy, and dual-energy CT are not be as widely available as MRI. In evaluation of bone and cartilage lesions after acute ankle injuries, 3 Tesla MRI is the best available imaging technique. The first imaging study after trauma is usually an X-ray to exclude fracture. X-ray can also reveal avulsion fractures and large osteochondral defects in addition to fracture.

IS CLASSIFICATION NECESSARY?:

BME is a common condition following ankle sprains [3,5], and the talus is the most frequently affected bone in these cases [7]. Although specific classifications for BME lesions do not exist, there are defined classifications for OCL in the talus [21]. In the literature, classifications for BME have been made based on MRI evaluations of the knee joint [4,22]. Mink and Deutsch [23] defined BME as non-linear lesions without involvement of the cartilage tissue based on MRI evaluations of the knee joint. Vellet et al [22] classified BME lesions into reticular, geographic, linear, impacted, and osteochondral based on their architectural appearances and their relationships with cortical bone. Lynch et al [4] classified knee joint injuries based on MRI images. Type 1 lesions are slender signal changes in the metaphysis or epiphysis. Type 2 lesions are associated with a straight, dark cortical line and extend to the cortex. Type 3 lesions are described as linear signal losses not associated with the subchondral region and cortical bone.

IS TREATMENT NECESSITY?:

Whether BME requires treatment is controversial. There is no evidence in the literature regarding the incidence of progression from talus BME to OCL [3]. Since the progression risk of these lesions is unclear, treating them is the most appropriate approach. In our study, similar successful outcomes were achieved with each treatment method, and the treatment that provided the fastest clinical improvement was determined.

BME is characterized by localized hemorrhage and fluid accumulation in the spongy tissue of the bone. Failure to eliminate this intramedullary edematous condition and the continuation of the stress that caused it can adversely affect the intramedullary vascular circulation. When left untreated, lesions in the cancellous region can progress toward the cortical bone and the chondral area [3,4,24]. Conversely, there are studies suggesting that these lesions can heal without any treatment and can spontaneously improve within a few weeks [25]. Loading the extremity increases intra-articular hydrostatic pressure, leading to high pressure on the talus. This pressure can stimulate intraosseous nerve tissue, resulting in pain. If there is a subchondral bone injury, it can force joint fluid into the bone and cause progression to OCL [3,26]. If a fracture is detected in the cartilage or subchondral bone plate on MRI, weight-bearing should be avoided [27]. Although some studies suggest that BME lesions do not progress to cartilage tissue abnormalities as long as the subchondral layer remains intact [28], it has been noted that weight-bearing can also lead to progression of the lesion from cancellous bone to cartilage and subchondral bone [3,24]. In patients with ankle inversion injuries, BME lesions did not involve any injury that would alter the clinical outcome at the 3-month evaluation [20]. The clinical outcomes of patients with and without BME detected after ankle trauma were compared, and it was concluded that these lesions do not affect the clinical outcome [29]. In asymptomatic patients, these lesions can be seen on MRI for 6–12 months [12].

WHAT CAN BE DONE IN TREATMENT?:

The primary approach in conservative treatment is to prevent progression of existing spongious injuries. Subchondral damage may not be detected with imaging methods. Therefore, the possibility of undetected subchondral damage should always be kept in mind, and non-weight-bearing should be implemented, especially in cases of persistent clinical conditions. If subchondral damage is present, weight-bearing can lead to progression, thus a period of non-weight-bearing is necessary, and caution should be exercised in terms of rehabilitation and return to sports [3].

In a study involving patients with isolated OCL in the knee, 91% of patients returned to their pre-injury activity level within an average of 3.2 months or shorter [30]. Bone bruising is a benign condition that shows radiological resolution within 6–12 months [3,31]. OCL lesions in the talus can be visible on MRI for up to 17 months, but clinical improvements can occur much earlier [32]. Clinical improvement usually precedes radiological improvement. Therefore, MRIs were not performed during follow-up, and the 8-week follow-up evaluations were considered. Caution should be exercised when significant OCL is present near the subchondral bone. Small fractures that cannot be detected by MRI or CT may be present. Therefore, it is recommended to have a period without weight-bearing during rehabilitation and to return to sports more gradually [3].

Bone edema is a benign condition that resolves clinically within 6–8 weeks, but it can show persistent edema on MRI for 6–12 months. The presence of bone edema should not delay rehabilitation unless symptoms persist or there is significant edema near the subchondral plate [3].

After ankle sprains, the incidence of OCL ranges from 7.4% to 40% [4]. Isolated lateral ligament tears have an incidence of 11%, while syndesmotic injuries have an incidence of 78% [26]. Deltoid injuries have a reported OCL rate of 70% [5]. Patients with partial and complete ligament tears were excluded from the study due to their potential impact on prognosis.

LIMITATIONS:

However, this study did not investigate the inter-observer variability between MRI readings provided by 2 different radiologists. Variability in the interpretation of MRI can affect the reliability and consistency of the diagnosis of BME. Further studies should include the assessment of reliability in order to reduce the bias of observers. Another limitation is that our study was retrospective. This was further compounded by the generally short follow-up duration, largely due to the fact that recovered patients do not return for follow-up visits. The stated outcome can also be biased in terms of treatment adherence and patient compliance. Stricter treatment monitoring and documentation may give a more real and proper judgment on the efficacy of the different treatment options applied. In these patients, the condition does not allow for invasive procedures that may be required in a possible histopathological diagnosis. One weakness of using a plaster cast is its tendency to confine patients very shortly after being operated on, thereby causing complications like muscle atrophy and joint stiffness. Prolonged immobilization may cause problems with comfort and compliance in some patients. Crutches provide mobility while avoiding weight-bearing but can be cumbersome and restrictive to movement and can also cause long-term muscle weakness, and some patients have poor compliance to crutches. The walking boot allows a balance between immobilization and weight-bearing, but can also result in discomfort and requires good patient compliance to allow optimal healing of the injury. MRI is sensitive for BME, but might not delineate all subtle changes. While high-resolution MRI is usually adequate, accessibility and financial considerations can be a drawback for many patients.

Conclusions

Crutches, in combination with non-weight-bearing for 3 weeks, proved to be more effective than a short leg cast in the treatment of traumatic BME of the talus. Crutches ensured better improvements in AOFAS and VAS scores and thus may be indicated for potentially better pain control and functional recovery. Several studies have shown the potential harmful effects of bone edema on joint cartilage. Therefore, avoiding weight-bearing activities on the affected area in the early stages of injury should be the fundamental approach.