Dave P. Heller1,2, Natalie Hayes1,3, Brynn Proffitt1,4, Mary Rackers1, Alyssa Bayard1, Wen Liu2

1Rockhurst University, Kansas City, Missouri; 2University of Kansas Medical Center, Kansas City, Kansas; 3University of Nebraska Medical Center, Lincoln, Nebraska; 4Regis University, Denver, Colorado

Insertional Achilles tendinitis can result from repetitive loading and is common in runners. Symptoms include pain and noticeable swelling at the calcaneal insertion. PURPOSE: The purpose of this case study is to describe asymmetries in center of mass (CoM) acceleration during lateral drop landings (LDL) in a subject with unilateral insertional Achilles tendinitis. METHODS: A 45-year old male recreational runner was diagnosed by an orthopedist with right insertional Achilles tendinitis. Pilot data investigating the reliability of CoM acceleration during LDL showed peak acceleration differences that appeared to be limb dependent. These differences could be due to an alternate landing strategy. The study involved performing 30 alternating single leg LDL from a 30cm platform. The subject wore a smartphone with an accelerometer application in a running belt level with the CoM. We analyzed peak CoM acceleration in all three dimensions as well as net peak CoM acceleration. We compared mean peak CoM acceleration for right-(affected) vs. left-(unaffected) footed landings using unpaired ttests. RESULTS: Mean anteroposterior (AP) peak CoM acceleration differed significantly between affected (R) vs. unaffected (L) landings (R: -0.78 + 0.78g vs. L: -0.27 + 0.89g; p = 0.02). There were no significant differences between R vs. L landings in the mediolateral (p = 0.760), longitudinal (p = 0.204) or net peak CoM acceleration (p = 0.439). For a secondary analysis, we assumed the mean peak AP CoM acceleration should be 0 since the movement during a LDL occurs in the frontal plane. We compared R and L mean peak AP CoM accelerations with 0 using a one sample t-test. The R mean peak AP CoM acceleration differed significantly from 0 whereas the L mean peak AP CoM acceleration did not (p = 0.001 and 0.105, respectively). CONCLUSION: This case study explores asymmetries in CoM acceleration during a LDL in one runner with Achilles tendinitis. There was significant mean anterior (negative) peak CoM acceleration while landing on the affected foot compared to landings on the unaffected foot. This could be an indication of a compensatory landing strategy to protect the damaged Achilles or a pathological landing strategy as a result of the tendinitis. Further analyses of landings in runners with unilateral insertional Achilles tendinitis is warranted.

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