Accuracy

 Accuracy is what the Orthoscanner system is all about. We accept that prescription writing and cast-taking will vary from practitioner-to practitioner, but we have made great efforts to bench-mark our own work and compare this with figures given by respected practitioners. We have found that rarely are the same posting values given for the same patient. Following assessment and having witnessed the procedures employed at the laboratory practitioners will invariably accept the accuracy of the scanner. No other scientific machine exists at present that could be used for comparison or calibration purposes.

 Quantifying Abnormality   It is also virtually impossible to accurately measure a dynamic, complex,  three dimensional foot and supporting limb during gait without the Orthoscanner. A two dimensional measuring tool such as a goneometer or protractor with the patient at rest requires a great deal of experience and approximation. It is our feeling that, although clinical judgement will always remain the cornerstone of practice, some methods of checking data scientifically rather than artistically is required especially when accuracy is critical for midfoot or forefoot control

 Recognition of functional disorders.  It is our experience that only well read and skilled practitioners are capable of regularly recognising biomechanical disorders on the couch. Training and supervision initially may be the reason why standards are generally poor and vary so tremendously.

 Compensation throughout the skeletal frame. This part of patient analysis takes many years of experience to associate with lower limb disorder. It is probably the area of work least understood. Ambulatory, dynamic measurement in surgeries without the Orthoscanner is also impossible for the following reasons:-

•          All frames must be captured simultaneously as opposed to sequentially.
•          All cardinal body planes must be seen together to assess compensation.
•          The tri planer axis of joints from the lumbar spine to the foot must be available.
•          Measurement must be accurate at the moment of capture and at 90 degrees to the plane.
•          Measurement has to be made during dynamic ambulation over several steps.
•          All phases of the gait cycle must be examined.
•          It is essential that the practitioner knows what they are looking for.
  
  

  Orchestration of movement. Observing and quantifying asymmetries or abnormalities as mentioned above is essential if normality is to be restored or attempted. This again requires experience along with accurate prescription writing. It is essential that the moment of compensation is known along with the degree of deformity at that time for many conditions will respond better if instead of treating what is seen on the couch only the degree of deformity at the moment of compensation is addressed. Again this is difficult in the surgery. Over control can be just as damaging to achieving symmetry and flow as under control.

   Prescription writing.  To some extent this has been dealt with above , however, good results require accurate prescription. The Orthoscanner system was designed for accuracy and to our knowledge cannot be challenged by practitioners or by other equipment.

   Fabrication.  The majority of foot orthoses supplied in the UK are the traditional thermoformed variety. The quality and accuracy of these devices vary tremendously depending on the experience of the fabrication laboratory. It should be said that some are excellent. More recently CAD/CAM milled devices have become available but are not without their critics. Irrespective of which method is used they all should conform to the following guidelines for accuracy :-

   In the surgery

   

  • Good cast taking. (Most laboratories agree that at least 70% of casts are taken badly.)
  • Accurate prescription writing.
  • A knowledge of what can be achieved with each patient

   At the laboratory (Traditionally)

   

  • Careful cast appraisal. (This requires experience)
  • Good cast adjustment if taken badly
  • Accurate cast marking
  • Accurate cast pouring to reflect angles required.
  • Experienced and skilful plaster additions for correction
  • Experienced orthoses design to the correct dimensions.
  • Correct temperatures and procedures during thermoforming.
  • Posting procedures and values must be accurate.
  • Finishing and polishing must not destroy the values.

   At the laboratory (CAD/CAM milling)

   

  • Careful cast appraisal. (This requires experience)
  • Good cast adjustment if taken badly
  • Accurate cast marking
  • No cast reduction by severe trimming to visualise the plantar surface.
  • Accurate and reproducible angular positioning for scanning purposes.
  • Modern software that can make adjustments on all planes
  • Skilled orthoses designer
  • Good design software package.
  • Calibration package must be accurate on all planes.
  • Good quality milling machine that can eliminate vibration.
  • Good quality of finish to eliminate the need to hand finishing and destroy accuracy.
  • Quality control procedures.