The accuracy of first metatarsophalangeal joint palpation guided injections. An arthrography cadaveric study

Background
Injectable glucocorticoids are widely used in the management of foot pathology, in particular for the treatment of osteoarthritis of the great toe - hallux limitus/rigidus. Injections can be performed using anatomical (blind) guided methods or performed with needle placement aided by the use diagnostic imaging with ultrasound or fluoroscopy, with or without the use of contrast media.

Aim
Palpation and image guided injection techniques have been studied in other joints of the body but less so for the first metatarsophalangeal joint of the foot, where palpation guidance is commonly performed. The aim of this study was to investigate the injection accuracy of palpation guided injections of the first metatarsophalangeal joint in six cadaveric feet using radio-opaque contrast media.

Methods
The injection equipment consisted of a 2.5ml Luer lock syringe and a 23-gauge needle used to inject iohexol (Omnipaque 300) into the first metatarsophalangeal joint in six cadaveric specimens. The needle was placed into the joint space by a single practitioner using palpation guidance. The contrast media was injected under live (cine) view without further movement or ingress of the needle. The injectate was considered accurate if the media coated the inside of the synovial membrane and/or outlined the joint shape.

Findings
Failure of technique was seen in one of six feet, and extravasation of contrast media beyond the joint margins noted in three out of six feet.

Conclusions
Further study on a large sample of live subjects using a variance of technique is required to expand the confidence of these findings but the high failure rate calls into question the confidence of palpation guided techniques for injection of the first metatarsophalangeal joint.