Clinical impact of 99mTc-HDP SPECT/CT imaging as standard workup for foot and ankle osteoarthritis

Abstract

Objective: The primary aim of this study was to assess to what extent 99mTc-HDP Single photon emission computed tomography/computed tomography (SPECT/CT) will lead to change of diagnosis and treatment, in patients with suspected foot and ankle osteoarthritis (OA). Secondary aim was to assess the intraobserver variability.

Methods: Retrospectively 107 patients, with suspected foot and/or ankle OA of which a SPECT/CT was made, were included for analysis. All the clinical and radiological data were randomized and blinded before being scored by one experienced orthopaedic surgeon. Firstly, based on the clinical data and conventional radiographs, a diagnosis and treatment plan was scored. Secondly, the observer accessed the SPECT/CT and could change the diagnosis and treatment plan. Additionally, the intraobserver reliability was determined by data of 18 patients that were added in twofold to the dataset, without awareness of the observer and by calculating the κ values.

Results: The diagnosis changed in 53% (57/107) and treatment plans changed in 26% (28/107) of the patients. Intraobserver reliability for the conventional workup was k = 0.54 (moderate strength of agreement), compared to k = 0.66 (substantial strength of agreement) when SPECT/CT data were added.

Conclusions: This study describes the influence of SPECT/CT on diagnosis and treatment plans in patients with suspected symptomatic OA. Also, it shows SPECT/CT leads to a higher intraobserver variability. We believe SPECT/CT has a promising role in the workup for foot and ankle OA.

Advances in knowledge: In addition to what was found in complex foot and ankle cases, this study shows that in patients with non-complex foot and ankle problems, SPECT/CT has a substantial influence on the diagnosis (and subsequent treatment plan).

Figure 1.

This patient (female of 50 years old) was treated 2 years before presenting for a stress fracture of the second metatarsal. However, her pain was persistent. On examination there was a mild swelling over the midfoot and there was tenderness when applying pressure at the midfoot. The X-rays did not show any abnormalities. The observer scored this case initially as no arthrosis. After assessing the SPECT/CT, the diagnosis was changed in navicular cuneiform OA and tarsometatarsal OA of the first ray. Before access to the SPECT/CT, the observer prescribed painkillers, after the SPECT/CT the plan was an ultrasound guided injection.

Figure 2.

This patient (male of 64 years old) has a premedical history of excision of a chondral lesion and a corrective osteotomy for equines around 30 years ago. Since 5 years, there is a progressive pain on the lateral side-of the foot and midfoot. On examination, the foot is in slight varus but is correctable, The foot can dorsoflex no more than 5 degrees because of stiffness. There is pain when applying pressure over the talocrural joint, subtalar joint, and talonavicular joint. The X-ray showed mild OA of the talocrural joint and the talonavicular joint. The observer scored this case as talocrural, subtalar and talonavicular OA. After the SPECT/CT, the diagnosis changed in only talocrural OA. The suggested treatment plan was an orthopaedic shoe and did not changed after evaluating the SPECT/CT.

Figure 3.

This patient (female of 60 years old) has pain of the foot and ankle for several years now. The ankle is stiff and painful, especially in the morning. On examination, the foot has valgus deformity and is not correctable. The talocrural joint has good function. Inversion is only 5 degrees and eversion goes up to 30 degrees. Not specifically painful. The X-ray showed OA of talocrural and talonavicular joint. The diagnosis initially was talocrural and talonavicular OA, while after the SPECT/CT it was subtalar OA. The treatment plan for this patient was an orthopaedic shoe and did not changed after the SPECT/CT.

Figure 4.

This patient is a 77-year-old male with no history of trauma. Since one and a half years, he has progressive pain and swelling of his right ankle after hiking and playing tennis. On examination, there is a mild varus axis and mildly swollen ankle. Although talocalcaneal is stiff, it is pain free on passive motion. There is mild pain while applying pressure subtalar on the medial side. The X-ray showed OA of the ankle with a asymmetrical joint line and possible subtalar OA. The diagnosis initially was talocrural and subtalar OA. SPECT/CT showed only OA and focal uptake in the sinus tarsi. The treatment plan changed from ultrasound-guided injection to an ankle arthrodesis.