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What are the effects on the stiffness of the 4th ray following lateral ankle sprains?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Dikoson, Dec 15, 2006.

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  1. Dikoson

    Dikoson Active Member


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    I have had quite a few patients in the last 2 months who i have been treating following lateral ankle sprains of varying severity.

    Three of them have been slightly unusual. 2 had moderate injuries treated conservatively, neither had fractures but both sustained significant ATFL tears (partial). During their rehab both developed dorsal pain at the base of their 4th metatarsal. Both patients had plantarflexion/inversion injuries as a mechanism. No prior injuries.

    On exam both had significantly reduced stiffness in their 4th ray (i.e its ROM was at least twice that of the unaffected limb). Both have settled with rigid custom orthotics.

    The third patient was different. She has a mechanically unstable ankle (ATFL insufficiency). She has declined surgery. First injury resulting in avulsion fracture was 5 years ago. Episodes of instability are weekly now despite decent physiotherapy input. No foot orthoses/orthotic intervention prior to seeing me this week. 2 years ago she developed a mortons neuroma in same side between 3/4 toes. This was dorsally excised. Neuroma recurred 14 months later and was again revised surgically with a plantar approach. She now has a 3rd recurrence! MRI confirms neuroma and no ligamentous abnormalities.

    On exam she is excessively pronated throughout stance, significant functional hallux limitus confirmed via in shoe analysis. Ankle joint rom is good, 15 deg dorsiflexion fully extended. Ankle proprioception poor. STJ axis medially deviated, MTJ ROM's acceptable as are other ROM's. However the 4th ray is as stiff as wet lettuce! If any joint was ever "hypermobile" this one is. She is in temporary orthotics while her custom devices are being made.

    Chris Nester's lecture at PFOLA in chicago got me thinking. In any patient experiencing a moderate/severe lateral ankle sprain, how commonly is the 4th ray loaded to a point where its proximal ligamentous structures are damaged?
    Has this been investigated/documented? I have searched and cannot find any mention of 4th ray deficiency following lateral ankle spain!

    Any comments welcome

    Sincerley

    Simon
     
    Last edited: Dec 15, 2006
  2. Simon:

    When you say the 4th ray stiffness is reduced, are you referring to dorsiflexion stiffness or plantarflexion stiffness? I would tend to doubt that the ligaments of the 4th metatarsal-cuboid joint could be disrupted without associated pain in that same joint. I see many inversion ankle sprains but have seen very few patients with inversion ankle sprains also complaining of 4th ray symptoms after the injury (however, 5th ray trauma is common in these injuries). Maybe you can explain this a little further, Simon. How do you assess 4th ray stiffness and why do you think the stiffness is decreased with inversion ankle sprains?
     
    Last edited: Dec 16, 2006
  3. Dikoson

    Dikoson Active Member


    Kevin,

    Aplogies for the delay in answering, been dealing with family illness.

    Reading back my post and your comments I shall endeavour to clarify the raised points.

    All patients appeared to have reduced dorsiflexion stiffness in the 4th ray. This was clinically assessed in compraison to the other foot. Although hard to quantify all 3 paients had significantly increased 4th ray dorsiflexion in comparison to the 3rd ray and sound side.

    As for how this occurs... here's my thoughts

    Plantarflexion/inversion injuries must increase the stresses on lateral forefoot structures. As the fifth ray is excessively loaded, pressure and force will be transferred to the 4th MTH as the fifth ray dorsiflexes. As the ankle complex inverts does the the 4th metatarsal sometimes experience so much force that it dorsifles relative to the midfoot causing ligamentous injury to the plantar ligaments of the 4th rays proximal articulations??? It must...or am i off the mark?

    Best wishes

    Simon
     
  4. Simon:

    This certainly sounds like a mechanically sound theory. I do see a significant number of 5th metatarsal fractures as a result of inversion ankle sprains so I see no reason why the same pathological dorsiflexion loading forces that cause a 5th metatarsal fracture couldn't also stretch or tear the ligaments of the plantar 4th metatarsal-cuboid joint or the short or long plantar ligaments. I'll try to look at this over the next few months in my own patients to see if I also see a correlation.
     
  5. efuller

    efuller MVP

    The load, during an ankle sprain, occurs with the foot markedly inverted. So, the direction of force is more likely to be lateral to medial as compared to plantar to dorsal. Any damage to the 4th cuboid joint, from the forces occuring during the sprain, are going to applied through the 5th met in a lateral to medial direction. So, if the 4th is damaged the 5th should be too. The majority of 5th met fractures related to ankle sprains are avulsion of the peroneus brevis tendon's insertion on the stloid. The mechanism of injury is the the foot is inverting with high supination moment and the body's response is to use the peroneous brevis to increase pronation moment. This leads to very high tension in the tendon and either the supination motion is decelerated or there is rupture somewhere in the system.

    Just a thought, lateral to medial force on the 5th met will cause abduction of the forefoot on the rearfoot. One of the structures that limits this motion is the calcaneo navicular ligament. It is possible to get rupture of this ligament or an avulsion fractrue of the anterior process of the calcaneus where this ligament attaches. This might cause an alteration in feel of the range of motion. However, your description seemed quite precise about the location of the pain and location of the motion, so this may not be it. The only reason that I suggest it, is because I'm having hard time explaining the mechanism of how an ankle sprain could cause 4th met cuboid hypermobility. It would be easier to explain decrease dorsiflexion stiffness of the 4th and 5th rays causing the ankle sprain.

    Regards,

    Eric
     
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