SLR - December 2014 - Stephanie Florence

The Influence of Knee Position on Ankle Dorsiflexion - A Biometric Study

Reference: Baumbach SF, Brumann M, Binder J, Mutschler W, Regauer M, Polzer H. The Influence of Knee Position on Ankle Dorsiflexion - a Biometric Study. BMC Musculoskelet Disord. 2014 Jul 23;15:246.

Scientific Literature Review

Reviewed By: Stephanie Florence, DPM
Residency Program: Bethesda Memorial Hospital - Boynton Beach, Florida

Podiatric Relevance:
Limited ankle joint dorsiflexion (ADF) is correlated to a variety of pathologies including but not limited to stress fractures, metatarsalgia, heel pain, and Achilles tendinopathy. This article discusses how increased ADF can prevent the pathologies listed. The most common restraint leading to decreased ADF is a tight gastrocnemius muscle. The authors relate that it is critical during examination, via the Silfverskiold test, to assess ADF with both the knee extended and then flexed. If it is found that ADF is increased once the knee is flexed then it is a tight gastrocnemius muscle that is inhibiting ADF. The authors state it is important to account for the degree of knee flexion needed for an increase in ADF to occur.

Literature has not examined the degree of knee flexion needed to influence ADF. The authors of this study examined varying degrees of knee flexion in relation to ADF. This article can help clinicians assess the proper exam technique for gastrocnemius influence on ADF. This will better aid them in deciding if the patient could benefit from stretching or a surgical gastrocnemius recession.

Methods: ADF measurements were taken of 20 symptomatic adults ranging from 18-40 years of age with 1:1 male to female ratio. ADF measurements were conducted both weightbearing and non-weightbearing at varying degrees: 0, 20, 30, 45, 60, 75, and Lunge. Two blinded investigators examined each patient and measurements were taken using the same style goniometer with 2-degree increment markings. Landmarks were the long axis of the fibula and fifth metatarsal shaft. Weightbearing assessment was done by having the patients stand in a lunge position while wearing a brace that controls various angles at the knee joint. The non-weightbearing measurements were taken with the patient supine while the subtalar joint was in neutral and the ankle joint maximally dorsiflexed. The final test performed by each patient was the Lunge test in which the patient was asked to perform a lunge with the rear leg flexed at a point just before the heel lifts off the ground all while subtalar joint neutral was maintained. The rearfoot was aligned with a marking on the floor perpendicular to the wall. ADF measurements were taken using the long axis of the fibular and the ground.

Results: The average ADF for non-weightbearing was 4 degrees with knee extended and 20 degrees ADF with knee flexed at 75 degrees. The mean weightbearing ADF was 25 degrees with knee extended and 39 degrees ADF with knee flexed at 75 degrees. The average difference between 20 degrees knee flexion and full extension was 15 degrees non-weightbearing and 13 degrees weightbearing. The only significant difference in ADF was found between full extension and 20 degrees knee flexion. Additional knee flexion did not increase ADF.

Conclusions: Knee flexion at 20 degrees fully eliminates ADF restraints of the gastrocnemius muscle. This is essential for clinicians to properly perform the Silfverskiold test, which is used, along with symptomatic pathology, to determine if the patient is a candidate for either stretching or surgical muscles recession.

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