Introduction: Pain is the key symptom of patients suffering of osteochondral lesion (OCL) of the ankle. However, its tissue origin and the pain inducing and modulating mechanisms remain controversial. Cartilage is aneural and unlikely causing pain. Contrary soft and bone tissue show rich nociceptive innervations. Routine radiographic imaging of OCL fails to visualize the pain inducing structure. Recent studies demonstrated the capability of planar scintigraphy and SPECT for localizing painful joints in degenerative joints conditions. However, a limited spatial resolution of bone scans compromises an accurate anatomical localization of an uptake. Single photon emission computed tomography – computed tomography (SPECT-CT) is a new hybrid imaging technique allowing perfect overlay of functional and anatomical images. In OCL, SPECT-CT identifies the exact location of an OCL and determines the spatial extent of pathological bone remodeling. We conducted a study to evaluate the correlation between pathological uptake within an OCL and pain experienced by patients.

Methods: 15 patients (7 female, 8 male; mean age 39, range 20–61 years) were assessed for unilateral OCL of the talus (13 joints) or distal tibia (2 joints). Radiological imaging of the foot and ankle consisted of plain radiographs, MRI and SPECT-CT. Clinical examination included range of motion (ROM), AOFAS Ankle-Hind-foot Scale, and pain status measured by the visual analogue scale (VAS). On completion of radiological and clinical assessment, patients were referred to the interventional radiology department for a diagnostic ankle injection. CTguided ankle joint injection with local anesthetics and iodine contrast medium was performed. Exact location of the deposit was documented.

VAS score was assessed immediately post-infiltration and compared to the pre-interventional VAS score. Pain relief was defined as a reduction of VAS score of more than 50% of the pre-intervention score immediately after infiltration.

The study was approved by the institutional review board and written informed patient consent was obtained. The study was carried out in accordance with the World Medical Association Declaration of Helsinki.

Results: All infiltrations were technically successful. Pre-interventional VAS score was 5.3 (range 2 - 10; SD 2.33). Post-interventional VAS score was 1.1 (range 2 – 4; SD 1.45). This difference was statistically significant (p < 0.01).

Discussion: The results of our study show a highly significant correlation between pain in OCL and pathological uptake seen on SPECT-CT, indicating bone as a major contributor to pain in this disease. Hybrid SPECT-CT technique is a new and powerful approach to diagnosis and staging of osteochondral lesions and provides important data for adequate treatment.

Introduction: Determination of the origin of chronic foot pain in osteoarthritis (OA) is challenging since clinical examination of the foot faces a complex anatomy with several joints, osseous, and non-osseous structures contributing to the symptoms. Non-invasive imaging methods (Rx, CT, MRI) show a poor correlation with pain degree. Studies using functional imaging based on the detection of activated osteoblasts with 99mTc-Dicarboxypropandiphosphate (DPD) to indicate painful facet joints show promising results, but so far no evaluation for chronic OA pain conditions in foot joints has been conducted and the diagnostic potential was limited due to poor spatial resolution of the scintigraphic assessment.

Single Photon Emission Computed Tomography – Computed Tomography (SPECT-CT) combines metabolic information with an exact anatomical localization. We hypothesised that diagnostic infiltration with a local anaesthetic of a painful hindfoot or midfoot joint showing 99mTc-DPD-uptake in SPECT-CT, leads to a positive OA pain response.

Methods: 26 patients with chronic OA pain and radiological signs of OA in a hindfoot or midfoot joint (27 feet) were included. Plain radiography was performed to detect degenerative changes and to rule out pathologies different from OA. Pain status was measured by Visual Analogue Scale (VAS). AOFAS hindfoot/midfoot score and SF-36–score were documented. All patients received a 99mTc-DPD SPECT-CT (Symbia T2, Siemens). The localisation of 99mTc-DPD-uptake and consequently the site of infiltration were defined. The infiltration was performed with a local anaesthetic (bupivacaine) and iodine solution under CT-guidance with exact documentation of the contrast media deposit by CT. Pain status was assessed directly post-infiltration. Pain relief in responders was defined as reduction of VAS-score > 50% immediately after infiltration, partial response as reduction of < 50%.

Results: Infiltration was performed in 26 hindfoot joints and 5 midfoot as indicated by 99mTc-DPD-uptake in SPECT-CT. Subsequent CT control scans showing contrast media depot confirmed exact successful infiltration in all indicated joints. In 22 patients an immediate significant (p< 0.01) postinterventional pain reduction of VAS more than 50% was observed. Mean VAS before infiltration was 5.77 (range 2–10; SD 2.22) and 0.82 (range 0–4; SD 1.26) immediately after infiltration. Two patients showed a partial response and one patient showed no pain resolution after infiltration.

Conclusion: The results show a significant correlation of uptake and pain resolution after infiltration allowing precise identification of OA hindfoot joints as pain inducing foci. SPECT-CT offers good prediction of outcome after infiltration improving the localisation of the pain inducing joint, thus aiding in pre-operative planning.

Purpose: Osteoarthritis (OA) is a common disease with increasing prevalence and rising socioeconomic burden. Of all symptoms accompanying OA, pain is the most disabling and frequent and the major reason why patients affected seek medical help. The determination of the origin of chronic foot OA pain is challenging since clinical examination of the foot faces a complex anatomy with several joints, osseous, and non-osseous structures contributing to the symptoms. For OA non-invasive imaging methods like plain radiograph, CT or MRI underestimate the degree of degenerative changes and show a poor correlation with pain degree. Studies using functional imaging based on the detection of activated osteoblasts with 99mTc-Dicarboxypropandiphosphate (DPD) to indicate painful facet joints in the lower spine show promising results, but so far no evaluation for chronic OA pain conditions in foot joints has been conducted and the diagnostic potential was limited due to poor spatial resolution of the scintigraphic assessment. Single Photon Emission Computed Tomography – Computed Tomography (SPECT-CT) is a new hybrid technique combining metabolic information with an exact anatomical localization. We hypothesised that diagnostic infiltration with a local anaesthetic of a painful hindfoot or midfoot joint showing 99mTc-DPD-uptake in SPECT-CT, leads to a positive OA pain response.

Method: 26 patients with chronic OA pain and radiological signs of OA in a hindfoot or midfoot joint (27 feet) were included. Plain radiography was performed to detect degenerative changes and to rule out pathologies different from OA. Pain status was measured by Visual Analogue Scale (VAS). AOFAS hindfoot/midfoot score and SF-36-score were documented.. All patients received a 99mTc-DPD SPECT-CT (Symbia T2, Siemens). The localisation of 99mTc-DPD-uptake and consequently the site of infiltration were defined. The infiltration was performed with a local anaesthetic (bupivacaine) and iodine solution under CT-guidance with exact documentation of the contrast media deposit by CT. Pain status was assessed directly post-infiltration. Pain relief in responders was defined as reduction of VAS-score > 50% immediately after infiltration, partial response as reduction of < 50%.

Results: Infiltration was performed in 26 hindfoot joints and 5 midfoot as indicated by 99mTc-DPD-uptake in SPECT-CT. Subsequent CT control scans showing contrast media depot confirmed exact successful infiltration in all indicated joints. In 22 patients an immediate significant (p< 0.01) postinterventional pain reduction of VAS more than 50% was observed. Mean VAS before infiltration was 5.77 (range 2–10; SD 2.22) and 0.82 (range 0–4; SD 1.26) immediately after infiltration. Two patients showed a partial response and one patient showed no pain resolution after infiltration.

Conclusion: The results show a significant correlation of uptake and pain resolution after infiltration allowing precise identification of OA hindfoot joints as pain inducing foci. Non-invasive SPECT-CT offers good prediction of outcome after infiltration improving the localisation of the pain inducing pathology, thus aiding in pre-operative planning and avoiding unnecessary interventions, as diagnostic infiltrations, with its possible risks and side effects.