Case History demonstrating the biomechanical jig saw puzzle – by trevor prior

A male patient with right hip pain demonstrates (bilateral unless stated):

  • 1st MTPJ dorsiflexion 60°.
  • The forefoot is inverted on the rearfoot.
  • On weight-bearing, both feet are pronated with calcaneal eversion and some lowering of the arch. There is increased medial navicular drift on the right.
  • Foot posture index 6 (Reference values – Highly supinated: -5 to -12, Supinated: -1 to – 4, Normal: 0 to + 5, Pronated: +6 to +9, Highly pronated: 10+).
  • There was no obvious functional or structural leg length discrepancy.

Inshoe pressure analysis indicated a more rapid transfer of load medially on the left. However, early loading of the hallux on this side was suggestive of poor limb control. We have observed two loading patterns when there is evidence of poor over all limb control – In some patients, they will load the lateral border of the foot on some steps and the medial border on others, we term this step to step variation. In some patients, the hallux loads very early in the step in an attempt to stabilise the foot. Whilst the former appears to stabilise well with orthoses, the latter function rarely resolves with orthoses alone.

The inshoe system was used to trial modified off the shelf orthoses. A pair designed to facilitate 1st MTPJ dorsiflexion with heel raises to offset some calf inflexibility provided the most symmetrical loading pattern but there was still early left hallux loading.

The patient returned 3 weeks later for 3d gait analysis and noted some improvement in the right hip symptoms.

I have selected some of the parameters to demonstrate this case. In this assessment, the patient is wearing shoes and pronation is rearfoot eversion. Values for the kinematic, flexibility and strength assessments are calculated statistically against a database of un-injured subjects.

The points to note are:

  • Rearfoot eversion is normal and symmetrical but there is asymmetrical tibial rotation. Given that there was a relatively symmetrical underlying structural alignment, this I suggestive that factors proximally to the foot are affecting function.
  • There is obvious excessive hip motion, worse on the right.
  • The orthoses have little effect on the foot and ankle but do improve right sided hip function.
  • There is less effect on left sided hip function consistent with our finding of early hallux loading not altering with the orthoses on inshoe analysis.
  • Analysis of the strength and flexibility assessment clearly show the deficits. It is likely that the excessive left sided tibial rotation is due to the excessive hip rotation whilst the reduced right sided tibial rotation is due to inflexibility.

This case demonstrates the complexity of assessing function and the many parameters that need to be considered.

In this case, the functional capacity indicated that there would be a tendency to pronation (lower arch / everted calcaneus, foot posture index 6) but one would expect relatively symmetrical function. Inshoe analysis was suggestive of poor limb control (i.e. factors proximal to the foot) and these features could only be modified to an extent with the orthoses used.  The strength and flexibility assessment demonstrates deficits which have the ability to alter function. By utilising 3d kinematic analysis and comparing to a normal range, we can see the asymmetry that occurs and, based on the assessment can conclude that the strength and flexibility are driving function.

The orthoses have helped given the feedback but they have clearly not addressed the overall function and thus there is the potential for further injury. A good rehabilitation programme is required in conjunction with the orthoses.

The level to which these are addressed will be determined by the level to which the individual wishes to function. The higher the requirement, the higher the rehab.

At present, there is some disagreement regarding the optimum clinical assessments of foot structure, in part due to the lack of reliable inter examiner measures. Agreement and development of these measures, will allow for normal ranges to be produced and facilitate more objective clinical assessment.

Case history puzzle

Case history puzzle 2