Abstract
Dear Editor:
We read with great interest the study “Silfverskiöld’s Test in Total Ankle Replacement With Gastrocnemius Recession” by James K. DeOrio and John S. Lewis Jr. 2 The authors make an important point about the improvement of ankle dorsiflexion in total ankle replacement after gastrocnemius recession regardless of the intraoperative results of the Silfverskiöld test. This improvement was measured electronically in a series of patients, based solely on the intraoperative clinical test as performed by the senior author.
In appreciation of the fact that Foot & Ankle International is a teaching journal, read by trainees and residents all over the world, we believe it is important to point out that the Silfverskiöld test is properly performed with 2 hands. By placing the one hand at the level of the subtalar joint and the other around the midfoot, stabilizing the talonavicular joint, the clinician keeps the foot in a neutral pronation-supination position while dorsiflexing the ankle. Therefore, the influence of these joints on the clinical estimation of ankle dorsiflexion is minimized. This has been well described and depicted in numerous relevant studies and textbooks.1,3-5 Admittedly, in the original description, Nils Silfverskiöld himself did not clarify this point but rather overlooked the importance of the subtalar joint by referring to the gastrocnemius as a muscle crossing 2 (and not 3) joints.6,7
In the relevant figures of the recent study, the senior author is depicted holding the patient’s foot from the toes with the heel hanging free while passively dorsiflexing the ankle with the knee fully extended and flexed 30 degrees. As described in the text, this allows for the accurate measurement of the ankle’s dorsiflexion by superimposing lines on a digital photograph and measuring the angle with software. Most probably the author also performed the Silfverskiöld test with 2 hands and then held the foot from the toes in order to achieve a clear view for the digital photograph, which would allow for drawing of the respective joint’s lines. It would be useful however, especially for the more junior readers, to clarify this point as this specific paper by DeOrio and Lewis may be referenced a number of times in future studies.
Yours sincerely,