Comparison of MRI and local anesthetic tendon sheath injection in the diagnosis of posterior tibial tendon tenosynovitis

BACKGROUND: The modalities currently available to clinicians to confirm the clinical suspicion of posterior tibial tendinitis include MRI, CT, sonography, tenography, and local anesthetic tendon sheath injections. There are no reports in the literature comparing local anesthetic tendon sheath injection to MRI as tools for diagnosing posterior tibial tenosynovitis. METHODS: The authors reviewed the records of all patients with stage 1 posterior tibial tendon dysfunction between the dates of September 1, 2001, to November 21, 2004. Fifteen patients (17 ankles) had a local anesthetic injection into the posterior tibial tendon sheath and MRI for clinically suspected tenosynovitis of the posterior tibial tendon. RESULTS: Seventeen (100%) of 17 ankles had complete relief of symptoms after the local anesthetic tendon sheath injections. Fifteen (88%) of 17 ankles had abnormally increased fluid signal within the posterior tibial tendon sheath seen on MRI. Two of two ankles (100%), after having negative MRI findings, had complete relief with a local anesthetic tendon sheath injection. In addition, conservative treatment failed in these two patients, and they subsequently had tenosynovectomy with gross confirmation at surgery of inflammatory changes within the tendon sheath. These two patients had complete symptom relief after tenosynovectomy. CONCLUSIONS: Local tendon sheath injections and MRI are both reliable diagnostic tools. Injection of the posterior tibial tendon is an accurate, safe, and sensitive modality useful in patients in whom MRI studies are negative in the face of continued clinical suspicion.