Welcome to the Podiatry Arena forums, for communication between foot health professionals about podiatry and related topics.
You are currently viewing our podiatry forum as a guest which gives you limited access to view all podiatry discussions and access our other features. By joining our free global community of Podiatrists and other interested foot health care professionals you will have access to post podiatry topics (answer and ask questions), communicate privately with other members (PM), upload content, view attachments, receive a weekly email update of new discussions, earn CPD points and access many other special features. Registered users do not get displayed the advertisments in posted messages. Registration is fast, simple and absolutely free so please, join our global Podiatry community today!
If you have any problems with the registration process or your account login, please contact contact us.
Spatial orientation of the subtalar joint axis is different in subjects with and without Achilles tendon disorders
Claudia A Reule, Wilfried W Alt, Heinz Lohrer, Harald Hochwald Br J Sports Med doi:10.1136/bjsm.2010.080119
Quote:
Background There are many possible predisposing factors for Achilles tendon disorders suggested in the literature but their pathogenetic relevance is not proven in most cases. The asymmetric mechanical load distribution within the Achilles tendon during locomotion is frequently addressed as a major risk factor for Achilles tendon disorders. The spatial orientation of the subtalar joint axis (STA) may influence the Achilles tendon loading possibly leading to overload injuries.
Hypothesis There is a significant difference between the orientation of the STA in subjects with and without Achilles tendon pathologies.
Materials and methods 614 subtalar joint axes determined in 307 long-distance runners with and without Achilles tendon disorders were included. Achilles tendon disorders were defined as any Achilles tendon–related pain during or following running, existing for more than 2 weeks in the past. Motion analysis of the foot was performed using an ultrasonic pulse-echo-based measurement system. The orientation of the STA was expressed by two angles.
Results The mean inclination angle was 42±16° and the mean deviation angle was 11±23°. There was a significant difference (p=0.002) between the mean deviation angle measured in subjects with Achilles tendon pathologies (18±23°) and those without (10±23°).
Conclusions The results demonstrate a wide interindividual variability of the spatial orientation of the STA. In addition, the mean deviation angle in people with Achilles tendon pathologies is significantly more oblique than in people without. This finding indicates that the spatial orientation of the STA is related to the incidence of overuse injuries of the Achilles tendon in the investigated sample.
Only a quick scan so far, really interesting methodology. This jumped out: "Standard textbook descriptions of the subtalar axis should possibly be revised"
Actually, they have two of my papers referenced, one I authored, and the other, I was one of the coauthors.
Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.
Lewis GS, Cohen TL, Seisler AR, Kirby KA, Sheehan FT, Piazza SJ: In vivo tests of an improved method for functional location of the subtalar joint axis. J Biomechanics, 42:146-151, 2009.
Not really too sure about how accurate their STJ spatial location measurement method was unless they were careful to apply a constant plantar load to the forefoot while they put the STJ through a range of motion. In the device we designed and used in the Lewis et al study, we had a custom jig that applied a constant dorsiflexion moment at the ankle joint to "lock" the talus within the ankle joint to minimize ankle joint motion. I don't see any mention of this in their article.
It is nice to see that other researchers now realize that there is a "a wide interindividual variability of the spatial orientation of the subtalar joint axis".
Here is what I wrote in my original article on STJ axis location from 24 years ago.
Quote:
"However, the angular direction of the subtalar joint axis is not constant. It exhibits great variability from individual to individual. The commonly
recognized angular values for the orientation of the subtalar joint axis of 16° from the sagittal plane and 42° from the transverse plane are only averages.
Most, individuals, therefore, have subtalar joint axes that are angulated to the sagittal and transverse planes at much different angles than these average angular values.2
The great variability in the actual angulation of the subtalar joint axis in the sagittal, transverse, and frontal body planes is functionally significant, but, unfortunately, it is infrequently mentioned or reported in the literature."
[Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987.]
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Kevin- you may recall this was presented at iFab last year... Good to see it published.
Ian... Can you send me a copy also?
Ta
Craig:
I thought it looked familiar...I'm also glad to see it published since it may now possibly wake up the rest of the international biomechanics community to the fact that they can no longer assume, for kinetics studies, that the inversion-eversion axis of the foot is a longitudinal bisection of the foot.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Not really too sure about how accurate their STJ spatial location measurement method was unless they were careful to apply a constant plantar load to the forefoot while they put the STJ through a range of motion. In the device we designed and used in the Lewis et al study, we had a custom jig that applied a constant dorsiflexion moment at the ankle joint to "lock" the talus within the ankle joint to minimize ankle joint motion. I don't see any mention of this in their article.
It also assumes that there is no movement occurring in the ankle mortice. While maximally dorsiflexing the ankle might reduce this, I'm not convinced it is eliminated. But good work, none-the-less. All they need to do now, is make the jig small enough to be worn for dynamic studies.... Perhaps if they read the STJ axis locator paper they could have their ultrasonic wizardry fixed to a similar jig to the one we developed, Kevin?
In vivo determination of the Achilles tendon moment arm in three-dimensions.
Hashizume S, Iwanuma S, Akagi R, Kanehisa H, Kawakami Y, Yanai T.
J Biomech. 2012 Jan 10;45(2):409-13.
Quote:
Two-dimensional methods have been applied to determine the Achilles tendon moment arm in previous studies, although the talocrural joint rotates in three-dimension. The purpose of this study was to develop a method for determining the Achilles tendon moment arm in three-dimensions (3DMA). A series of sagittal ankle images were obtained at ankle positions of -20°, -10° (dorsiflexed position), 0° (neutral position), +10°, +20°, and +30° (plantarflexed position). The talocrural joint axis was determined as the finite helical axis of the ankle joint over 20° of displacement, and the 3DMA was determined as the shortest distance from the talocrural joint axis to the line of action of the Achilles tendon force. The corresponding 2DMA was determined with the center of rotation method using the images captured on the sagittal plane passing through the mid-point of the medio-lateral width of the tibia. The 3DMA ranged from 35 to 41 mm across various ankle positions and was, on average, 11 mm smaller than 2DMA. The difference between the two measures was attributable primarily to the deviations of the talocrural joint axis from the anatomical medio-lateral direction. The deviations on the coronal plane (21.4±20.7°) and on the transverse planes (14.8±22.6°) accounted for the errors of 1.3 mm and 3.0 mm, respectively. In addition, selecting either a medially or laterally misaligned sagittal-plane image for determining the 2DMA gave rise to error by 3.5 mm. The remaining difference was accounted for by the random measurement error.
Is Calcaneal Inclination Higher in Patients with Insertional Achilles Tendinosis?A Case-controlled, Cross-sectional Study
Naohiro Shibuya, Jakob C. Thorud, Monica R. Agarwal, Daniel C. Jupiter Jnl Foot Ank Surg (Article in Press)
Quote:
Insertional Achilles tendinosis is a condition where a patient complains of isolated pain at the Achilles tendon insertion site due to intratendinous degeneration. It has been suggested that this condition is associated with cavus foot deformity. However, to our knowledge, there is no study that has confirmed this observation. We carried out a cross-sectional, case-controlled study to explore the association of increased calcaneal inclination—a surgically important characteristic of cavus foot deformity—with insertional Achilles tendinosis. Patients with Achilles tendinosis and matched controls without the pathology were compared. Although a statistically significant difference was detected in calcaneal inclination angle between these 2 groups (p = .038), we felt that the difference was not clinically significant (calcaneal inclination angle = 20.9 vs. 18.9, respectively). Within the limitations of the study, we conclude that there is no clinically significant difference in calcaneal inclination between those with or without insertional Achilles tendinosis.
STJ Axis Variations and Achilles Tendonitis
Linear Mode
