Increased Osseous (99m)Tc-DPD Uptake in End-Stage Ankle Osteoarthritis: Correlation Between SPECT-CT Imaging and Histologic Findings

Ankle Osteoarthritis

Ankle osteoarthritis (OA) is less common than knee and hip OA, and 75% to 80% of all presentations are posttraumatic in nature, resulting from either ligamentous or bony injury to the ankle. While the ankle joint cartilage demonstrates capacity for self-restoration, the ankle joint is sensitive to aberrancies in biomechanics and the inflammatory milieu after an injury is thought to contribute to the onset of posttraumatic ankle OA. Conservative care for ankle OA is currently centered on pain reduction, and derivatives that may delay the progression of ankle OA are the subject of ongoing investigation. Surgical management for end-stage ankle OA currently focuses on ankle arthrodesis and total ankle arthroplasty. Specific indication for one procedure over the other is the topic of much debate. While total ankle arthroplasty has become more frequently used with the advent of newer generation systems, ankle arthrodesis may still be favored in younger patients with high-demand occupations.

Ankle osteoarthritis: comprehensive review and treatment algorithm proposal

Ankle osteoarthritis (OA) is much less frequent than knee or hip OA, but it can be equally disabling, greatly affecting the quality of life of the patients.

Approximately 80% of ankle OA is post-traumatic, mainly secondary to malleolar fractures, being another of the main causes untreated in chronic instability. The average age of the patient affected by ankle OA is around 50 years, being therefore active patients and in working age who seek to maintain mobility and remain active.

The authors conducted a comprehensive review of the conservative, medical, and surgical treatment of ankle OA.

Initial conservative treatment is effective and should be attempted in any stage of OA. From a pharmacological point of view, non-steroidal anti-inflammatory drugs (NSAIDs) and intra-articular infiltrations can produce temporary relief of symptoms.

After the failure of conservative-medical treatment, two large groups of surgical treatment have been described: joint-preserving and joint-sacrificing procedures.

In the early stages, only periarticular osteotomies have enough evidence to recommend in ankle OA with malalignment. Both ankle arthrodesis and ankle replacement can produce satisfactory functional results if correctly indicated in the final stages of the disease.

Finally, the authors propose a global treatment algorithm that can aid in the decision-making process.

Relevance of SPECT-CT in Complex Cases of Foot and Ankle Surgery: A Comparison With MRI

BACKGROUND

Finding the right diagnoses in patients with complex foot and ankle disorders can be challenging. Single-photon emission computed tomography and computed tomography (SPECT-CT) has shown to be feasible in foot and ankle surgery. The aim of this study was to evaluate the reliability and accuracy of SPECT-CT and thereby its impact on final treatment decision compared with magnetic resonance imaging (MRI).

METHODS

A retrospective study was performed on 49 patients treated at our institution. Experienced foot and ankle surgeons independently, and blinded, analyzed clinical data and radiographs together with MRI, SPECT-CT, or a combination of both. Based on the determined final treatment decision Cohen's kappa values were calculated to illustrate interrater and intrarater reliability.

RESULTS

The kappa values for interrater reliability were higher for SPECT-CT at .68 and MRI + SPECT-CT at .71 compared to 0.38 for MRI alone (P < .05). The kappa values for intrarater reliability of MRI + SPECT-CT were higher at .75 compared with SPECT-CT alone at .67 (P < .05) and MRI at .35 (P < .01).

CONCLUSION

We found a higher interrater and intrarater reliability for SPECT-CT compared with MRI alone for diagnosing complex foot and ankle pathologies. SPECT-CT has a high impact on final treatment decision. The main indications are bony pathologies with diagnostic uncertainty especially in closely adjacent structures as the joints of the midfoot, occult coalitio, stress fractures, verification or exclusion of nonfusion, periprosthetic disorders after total ankle replacement and osteochondral lesion in cases of combined pathologies.Levels of Evidence: Level IV: Retrospective study.

[Supramalleolar osteotomy in asymmetric ankle osteoarthritis : Short-term clinical and radiographic results]

BACKGROUND

The main indication for the supramalleolar osteotomy is asymmetric ankle osteoarthritis with concomitant supramalleolar valgus or varus deformity. The aim of this prospective study was to analyze short-term clinical and radiographic outcomes in patients with asymmetric ankle osteoarthritis.

METHODS

A total of 16 patients with asymmetric ankle osteoarthritis and concomitant supramalleolar deformity - 7 patients with valgus deformity, 9 patients with varus deformity - were treated. Intraoperative and postoperative complications were recorded and analyzed. The clinical and radiographic outcomes were assessed after a mean follow-up of 3.6 ± 1.1 years.

RESULTS

In 10 of 16 patients, removal of hardware was performed. The AOFAS hindfoot score increased significantly after surgery. All categories of the SF-36 score showed significant improvement. The average range of motion also increased significantly. Radiographic assessment showed neutral hindfoot alignment at the latest follow-up. The postoperative clinical outcomes were comparable in both patient groups. The time until complete osseous union was significantly longer in patients with opening wedge osteotomy.

CONCLUSION

This prospective study demonstrated encouraging short-term results in patients with asymmetric ankle osteoarthritis who underwent supramalleolar osteotomy. In progressive ankle osteoarthritis, joint-nonpreserving treatment options including total ankle replacement or ankle arthrodesis should be discussed.

The utility of the ankle SPECT/CT scan to predict functional and clinical outcomes in supramalleolar osteotomy patients

Combined single-photon emission computed tomography and conventional computed tomography (SPECT/CT) is a hybrid imaging modality that shows a combination of metabolic and structural information about the ankle, including arthritis. We hypothesize that uptake in specific locations within the ankle joint can be associated with both clinical outcomes and may help predict which patients will have a successful SMO. Eighty-five pre-operative SMO patients with varus (37), valgus (41), or neutral (7) alignment of the hindfoot were assessed using SPECT/CT. The level of activation on SPECT/CT scans was measured. Pre and Post-operative functional scores were recorded. Patients with medial gutter activation had significantly worse (p < 0.05) AOFAS alignment (AOFAS-A) scores pre-operatively. Patients with varus or valgus alignment did not have any difference in VAS pain scores, but those in valgus did have worse AOFAS-P (pain) scores. Those with cystic lesions had a worse FAOS score pre-operatively. Ten patients (12.5%) had a treatment failure. Pre or post-operative alignment did not correlate to a treatment failure. The only statistically significant (p = 0.036) poor prognostic indicator was a bipolar lesion. Pre-operative SPECT/CT evaluation of an ankle before a SMO can be used to clinically correlate patient-specific factors such as pain and function in the pre and post-operative period. We caution against performing a SMO in patients with bipolar activation on a pre-operative SPECT-CT scan. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2015-2021, 2018.

Novel Ex Vivo Human Osteochondral Explant Model of Knee and Spine Osteoarthritis Enables Assessment of Inflammatory and Drug Treatment Responses

Osteoarthritis of the knee and spine is highly prevalent in modern society, yet a disease-modifying pharmacological treatment remains an unmet clinical need. A major challenge for drug development includes selection of appropriate preclinical models that accurately reflect clinical phenotypes of human disease. The aim of this study was to establish an ex vivo explant model of human knee and spine osteoarthritis that enables assessment of osteochondral tissue responses to inflammation and drug treatment. Equal-sized osteochondral fragments from knee and facet joints (both n = 6) were subjected to explant culture for 7 days in the presence of a toll-like receptor 4 (TLR4) agonist and an inhibitor of transforming growth factor-beta (TGF-β) receptor type I signaling. Markers of inflammation, interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), but not bone metabolism (pro-collagen-I) were significantly increased by treatment with TLR4 agonist. Targeting of TGF-β signaling resulted in a strong reduction of pro-collagen-I and significantly decreased IL-6 levels. MCP-1 secretion was increased, revealing a regulatory feedback mechanism between TGF-β and MCP-1 in joint tissues. These findings demonstrate proof-of-concept and feasibility of explant culture of human osteochondral specimens as a preclinical disease model, which might aid in definition and validation of disease-modifying drug targets.

Increased bone tracer uptake in symptomatic patients with ACL graft insufficiency: a correlation of MRI and SPECT/CT findings

PURPOSE

Magnetic resonance imaging (MRI) and single-photon emission computerised tomography/computerised tomography (SPECT/CT) are used as diagnostic tools in symptomatic patients after reconstruction of the anterior cruciate ligament (ACL). The benefit of SPECT/CT in comparison with MRI is under debate. The purpose of this study was to investigate whether and how bone tracer uptake (BTU) intensity and distribution in SPECT/CT correlate with MRI findings in symptomatic patients after ACL reconstruction.

METHODS

Twenty-nine patients (male:female = 22:7, mean age ± SD 26 ± 10 years) with symptoms of pain and instability after ACL reconstruction were retrospectively investigated using prospectively acquired SPECT/CT and MRI. On MRI graft tear, graft signal intensity, bone marrow oedema, tunnel cyst formation, roof impingement, roof osteophytes, local arthrofibrosis, joint effusion and synovial thickness were analysed by two readers blinded to the BTU results. BTU was anatomically localised and volumetrically quantified. Spearman's rho test was used for correlation of BTU in SPECT/CT and MRI findings (p < 0.05).

RESULTS

SPECT/CT showed increased femoral and tibial BTU in patients with MRI-confirmed graft tear, signal hyperintensity of the intraarticular graft section, joint effusion, synovial thickening, roof osteophytes and bone marrow oedema. Cyst formation in the femoral tunnel results in significantly reduced BTU in femur and tibia. No correlation of increased BTU was found for graft impingement and graft arthrofibrosis.

CONCLUSIONS

Bone tracer uptake in SPECT/CT and defined MRI findings in symptomatic patients after ACL reconstruction were correlated. Both imaging modalities have a definite role in post-operative diagnostic and have established their value in those patients. This study provides a better understanding of the clinical value of SPECT/CT versus MRI in the clinical decision-making process. SPECT/CT provides a window into the in vivo loading of the joint as well as bone remodelling and graft incorporation process. In addition, ACL graft insufficiency can be detected by increased BTU.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

What drives osteoarthritis?-synovial versus subchondral bone pathology

Subchondral bone and the synovium play an important role in the initiation and progression of OA. MRI often permits an early detection of synovial hypertrophy and bone marrow lesions, both of which can precede cartilage damage. Newer imaging modalities including CT osteoabsorptiometry and hybrid SPECT-CT have underlined the importance of bone in OA pathogenesis. The subchondral bone in OA undergoes an uncoupled remodelling process, which is notably characterized by macrophage infiltration and osteoclast formation. Concomitant increased osteoblast activity leads to spatial remineralization and osteosclerosis in end-stage disease. A plethora of metabolic and mechanical factors can lead to synovitis in OA. Synovial tissue is highly vascularized and thus exposed to systemic influences such as hypercholesterolaemia or low grade inflammation. This review aims to describe the current understanding of synovitis and subchondral bone pathology and their connection in OA.

How To Diagnose and Treat Infection in Total Ankle Arthroplasty

Periprosthetic infection after total ankle arthroplasty (TAA) is a serious complication, often requiring revision surgery, including revision arthroplasty, conversion to ankle arthrodesis, or even amputation. Risk factors for periprosthetic ankle infection include prior surgery at the site of infection, low functional preoperative score, diabetes, and wound healing problems. The clinical presentation of patients with periprosthetic ankle joint infection can be variable and dependent on infection manifestation: acute versus chronic. The initial evaluation in patients with suspected periprosthetic joint infections should include blood tests: C-reactive protein and erythrocyte sedimentation rate. Joint aspiration and synovial fluid analysis can help confirm suspected periprosthetic ankle infection.

GEORG-SCHMORL-PRIZE OF THE GERMAN SPINE SOCIETY (DWG) 2016: Comparison of in vitro osteogenic potential of iliac crest and degenerative facet joint bone autografts for intervertebral fusion in lumbar spinal stenosis

PURPOSE

The promotion of spinal fusion using bone autografts is largely mediated by the osteoinductive potential of progenitors/mesenchymal stem cells (MSC) that reside in the marrow spaces of cancellous bone. Iliac crest is the common autograft donor site, but its use presents an increased risk for donor site pain, morbidity and infection. Degenerative bone samples harvested during facetectomy might provide an alternative viable source of osteoinductive autografts. In this study, we conducted an intra-individual comparison of the osteogenic potential of isolated low passage MSC from both sources.

METHODS

Iliac crest and degenerative facet joints were harvested from eight consecutive patients undergoing transforaminal lumbar interspinal fusion due to lumbar spinal stenosis. MSC were isolated by collagenase digestion, selected by plastic adherence and minimally expanded for downstream assays. Clonogenic and osteogenic potential was evaluated by colony formation assays in control and osteogenic culture medium. Osteogenic properties, including alkaline phosphatase (ALP) induction, matrix mineralization and type I collagen mRNA and protein expression were characterized using quantitative histochemical staining and reverse transcription PCR. Spontaneous adipogenesis was analysed by adipocyte enumeration and gene expression analysis of adipogenic markers.

RESULTS

Average colony-forming efficiency in osteogenic medium was equal between iliac crest (38 ± 12%) and facet joint (36 ± 11%). Osteogenic potential at the clonal level was 55 ± 26 and 68 ± 17% for iliac crest and facet joint MSC, respectively. Clonogenic and osteogenic potential were significantly negatively associated with donor age. Osteogenic differentiation led to significant induction of ALP activity in iliac crest (sixfold) and facet joint (eightfold) MSC. Matrix mineralization quantified by Alizarin red staining was increased by osteogenic differentiation, yet similar between both MSC sources. Protein expression of type I collagen was enhanced during osteogenesis and significantly greater in iliac crest MSC. Correspondingly, COL1A2 mRNA expression was higher in osteogenically differentiated MSC from iliac crest. Adipocyte numbers showed significant differences between iliac crest (63 ± 60) and facet joint (18 ± 15) MSC under osteogenic conditions. Negative (GREM1) and positive (FABP4) adipogenic markers were not differentially expressed between sources.

CONCLUSION

MSC from iliac crest and degenerative facet joints largely display similar clonogenic and osteogenic properties in vitro. Differences at the molecular level are not likely to impair the osteoinductive capacity of facet joint MSC. Bone autografts from facetectomy would be viable alternatives as bone autografts for intervertebral spinal fusion in lumbar spinal stenosis.

Technetium-99m Methylene Diphosphonate Single-photon Emission Computed Tomography/Computed Tomography of the Foot and Ankle

The complex anatomy and function of the foot and ankle can make it difficult to determine the cause of symptoms in patients with foot and ankle pathology. Following initial clinical and radiographic assessment, additional imaging with magnetic resonance imaging may be required, which is often seen as the modality of choice. Although sensitive to pathological changes in bone metabolism and vascularity, technetium-99m (Tc-99m) bone scintigraphy often lacks the specificity and resolution required to evaluate the structures of the foot and ankle. Tc-99m methylene diphosphonate single-photon emission computed tomography/computed tomography (SPECT/CT) combines this sensitivity with the superior anatomical detail of CT, enabling better localization of pathological uptake and evaluation of associated structural changes. As a result, SPECT/CT has been growing in popularity for the assessment of patients with foot and ankle pathology where it can provide additional information that may change the initial diagnosis and subsequent management plan. Studies have reported modification of the surgical approach and site of intra-articular local anesthetic injections following SPECT/CT with good results. Interpretation of SPECT/CT studies requires an understanding of the pathological changes that result in increased tracer accumulation in addition to the CT changes that may be seen. This review aims to highlight the advantages of SPECT/CT, potential applications and explain the imaging appearances of common pathologies that may be observed.

Characterization of subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis

Facet joint osteoarthritis may be a cause of low back pain in degenerative spine diseases including lumbar spinal stenosis. Subchondral bone is regarded as a potential therapeutic target for osteoarthritis treatment. The goal of this study was to characterize subchondral bone histopathology in osteoarthritic facet joints from lumbar spinal stenosis patients. Fifteen patients with degenerative spinal stenosis scheduled for transforaminal lumbar interbody fusion surgery were recruited for this study. Osteoarthritis severity was graded on T1- and T2-weighted MRI images using Weishaupt scoring system. Dissected osteoarthritic facet joints were subjected to histological and immunohistochemistry analyses to study relative abundance of osteoblast, osteoclasts, and macrophages using van Gieson's, tartrate-resistant acid phosphatase and CD68-antibody staining, respectively. Presence of nerve fibers was evaluated by PGP9.5-antibody staining. Differential bone histopathology, independent from radiological osteoarthritis grade, was observed in facet joints. Extensive de novo bone formation was found in subchondral bone tissues of eight of fifteen specimens. Regions of bone formation showed high abundance of blood vessels and CD68-positive macrophages, but were devoid of multinucleated osteoclasts. Additional pathological changes in subchondral marrow spaces, including inflammatory infiltration and enhanced osteoclast activity, were characterized by macrophage-rich tissues. PGP9.5-positive nerve fibers were detected near arterioles, but not in regions displaying bone pathology. Individual histopathological parameters did not associate with clinical features or radiological osteoarthritis severity. Subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis is characterized by marrow infiltration by macrophage-rich tissues and enhanced de novo bone formation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1475-1480, 2016.