Stress fractures in bones are caused by prolonged, possibly intermittent, traction force on areas of bone where muscle fibres attach, or where there is direct, increased load. They can be painful, most often during physical activity and are often debilitating, preventing physical activity.
One such, common, stress fracture, is that of the tibia at the site of the attachment of the propulsive, supinating muscles in the medial, posterior compartment of the lower leg. (Medial Tibial Stress Syndrome – MTSS). This condition is caused by overuse of those muscles, attempting to resupinate the foot during the late midstance and propulsive phases of running gait.
The overuse is caused by a structural and functional abnormality within the foot and lower leg that is creating a force that opposes that resupination. Effective treatment, apart from rest, involves the elimination of that opposing force.
These two case histories detail the history and treatment of two stress fractures within the foot. One is a sesamoid stress fracture in a professional rugby football player and the other a cuboid stress fracture in a ten year old athlete.
1. SESAMOID STRESS FRACTURE
The sesamoid stress fracture prevented this early twenties professional rugby seven’s player from training in the Australian Women’s team squad in preparation for the 2016 Olympic Games. This athlete is a valued and important member of the team. The onset of the foot problem had been gradual as there was chronic overload of the 1st metatarso-phalangeal joint with pain and blistering of the skin for many years. Unfortunately, this was not being addressed adequately and developed into the stress fracture.
On examination, the foot was found to be a high arched, cavus foot type with an inverted rearfoot position, an everted forefoot position with a forefoot valgus alignment plus a plantar flexed 1ST ray. This foot type places increased load through the 1ST MTP joint and sesamoids during the propulsive phase of gait. The game of Rugby Sevens is fast and explosive acceleration is required so players are sprinting on their forefeet for a lot of the time. Xrays confirmed the diagnosis with a marked stress reaction through the lateral sesamoid.
Examination was difficult as the forefoot was extremely painful. However, there was adequate plantar and dorsiflexion of the hallux when non-weight bearing, but this reduced dramatically in static stance with a functional hallux limitus. The rearfoot alignment was inverted with subtalar joint supination and an inverted calcaneus.
This subtalar joint supination occurs to not only offload the painful medial aspect of the forefoot but also when there is insufficient supination available around the longitudinal axis of the midtarsal joint to compensate the forefoot valgus alignment. With this maximum midtarsal joint supination the forefoot becomes unstable, the longitudinal arch lower than normal with tightening of the plantar fascia and flexor hallucis longus tendon, thus reducing the range of dorsiflexion of the 1ST MTP joint and increasing the load on the sesamoids. This restriction in dorsiflexion at heel off in the gait cycle causes an abductory twist of the leg with shearing stress on the skin plantar to the 1ST MTPJ, often causing blisters.
Treatment of the sesamoid stress fracture, apart from rest, involved a detailed biomechanical examination with measurement of hip range of motion, knee position, tibial or malleolar torsion and range of motion and position of the rearfoot and forefoot.
Measurement of the degree of forefoot valgus and plantar flexed 1st ray, with the patient lying prone, the subtalar joint held in neutral and midtarsal joint maximally pronated and locked was necessary to not only reach a definitive diagnosis of the underlying pathology but to also determine the prescription for appropriate orthoses. A 3D scan was taken of both feet and the forefoot alignment checked to ensure duplication of the measurements taken in the biomechanical exam.
The orthoses were made from high density EVA with a varus rearfoot posting and forefoot valgus posting extending to the distal end, tapering off at the toes. This forefoot valgus posting helps to lock the midtarsal joint and stabilise the forefoot. The prescription also incorporated a metatarsal dome to transfer load away from the 1ST MTPJ. The EVA plantar to the 1ST MTPJ was filled with soft Poron cushioning material. A 2mm multiform cushion layer was added to the top surface for comfort.
The orthoses were ground thin enough to fit Asics football boots and Asics running/training shoes that provided torsional stability through the midsoles. This athlete was able to return to full training and playing activity within a week following the dispensing of the orthoses and went on to win a gold medal with the team in the Olympic Games. She continues to wear the orthoses and remains pain free.
2. CUBOID STRESS FRACTURE
This was an unusual case in that this ten year old girl was otherwise very healthy and actively engaged in a variety of sports without any problems until this condition developed. Her foot shape, position and alignment appeared within normal limits.
The pain in the lateral side of her left foot developed relatively quickly and became debilitating, preventing any weight bearing activity. Examination of the foot proved difficult because of her apprehension of increased pain with any touch or attempt to move the foot.
Xrays showed a stress reaction in the cuboid bone. The lateral weight bearing view also showed an elongated anterior process of the calcaneus and a lateral oblique view showed a developing calcaneo-navicular coalition. Movement through this part of the foot had caused pain resulting in contractual spasm of peroneus longus to prevent any such motion. The constant pull on this tendon which passes directly inferior to the cuboid had resulted in the stress reaction. Attempts to stabilise the foot with taping and an air-cast boot did little to relieve the muscle spasm and pain in the cuboid.
The coalition was successfully removed surgically followed by prescription orthoses to stabilise the foot to reduce any excessive midtarsal joint movement. The peroneal muscle was then able to relax and the cuboid gradually returned to normal. This treatment proved effective and the patient was able to return to active sport without further complications.
If you've had a stress fracture, book an appointment with one of our podiatrists for an assessment.