Distinct hip and rearfoot kinematics in female runners with a history of tibial stress fracture. Journal of Orthopaedic & Sports Physical Therapy. 2010 Feb;40(2):59-66. Milner CE1, Hamill J, Davis IS.
Cross-sectional controlled laboratory study.
To investigate the kinematics of the hip, knee, and rearfoot in the frontal and transverse planes in female distance runners with a history of tibial stress fracture.
Tibial stress fractures are a common overuse injury in runners, accounting for up to half of all stress fractures. Abnormal kinematics of the lower extremity may contribute to abnormal musculoskeletal load distributions, leading to an increased risk of stress fractures.
Thirty female runners with a history of tibial stress fracture were compared to 30 age-matched and weekly-running-distance-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected using a motion capture system and a force platform, respectively, as subjects ran in the laboratory. Selected variables of interest were compared between the groups using a multivariate analysis of variance (MANOVA).
Peak hip adduction and peak rearfoot eversion angles were greater in the stress fracture group compared to the control group. Peak knee adduction and knee internal rotation angles and all joint angles at impact peak were similar between the groups.
Runners with a previous tibial stress fracture exhibited greater peak hip adduction and rearfoot eversion angles during the stance phase of running compared to healthy controls. A consequence of these mechanics may be altered load distribution within the lower extremity, predisposing individuals to stress fracture.
I thought this study was interesting because I have been reading studies and blogging on patellofemoral pain and plantar fasciitis. I’ve been finding there are likely similar causes/results from each condition, being hip adduction (the thigh moving more towards midline of the body) and or internal rotation and flat feet (AKA fallen arches, over pronation). This study found largely the same thing with tibial stress fractures in female runners. They did not find increased hip internal rotation but they did find increased hip adduction, and when they talk about “rearfoot eversion,” that is another measure of fallen arches or flat feet.
The researchers concluded that hip abduction strengthening and arch supports might be good for treatment and/prevention. Both of those sound reasonable, but I would suggest a general lower extremity and core strength training program. Though it is true the hip abductors do tend to be particularly weak, runners with patellofemoral pain and plantar fasciites have been found to have more global muscle weakness as well. Strengthening the foot intrinsic muscles might also help to support the arches and lessen tibial stress.
The researches also said:
“The greater hip adduction in the stress fracture group may be the result of the greater rearfoot eversion, or, conversely the greater hip adduction may be the cause of greater rear foot eversion.”
I was thinking this very thing with relation to plantar fasciitis and fallen arches. If the hips are weak and the thigh adducts and internally rotates, it puts increased stress on the arch of the foot, and might be causing a flattening effect on the feet. This may potentially result in foot conditions such as plantar fasciitis, posterior tibial tendinitis, acquired flat foot deformity, patellofemoral pain, and as this study indicates tibial stress fractures. And let’s not forget greater trochanteric pain syndrome/trochanteric bursitis. Even low back pain is associated with LE weakness. The picture coming together from all this research is that all of these problems stem from the same cause (generalized LE, and likely core, weakness) which perhaps isn’t so much overuse in running but rather underuse of strength training. The result is muscles aren’t strong enough to properly support bones and joints, causing breakdown of tissue wherever the weak link in the chain is (be it the hip, knee, tibia, ankle or foot). Worse is that injury of the weak link alters running and walking mechanics, and often due to disuse leaves the rest of the chain in a weakened condition, more prone to further injury.
Knowing all this I’m going to go out on a limb and suggest that passive modalities (stretching, soft tissue mobilization, foam rolls, ultrasound, dry needling, kinesio tape, or whatever the current fad is) in physical therapy probably isn’t the best use of anyone’s limited resources. Probably it’s better to add some balanced and well prescribed strength training to your running program. The good news is that while one should take time off from running to let a stress fracture heal, there is a lot of strengthening that can be done both above and below the fracture site that won’t place any stress on it.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.