NDS Scientific Research - Neural Aspect Patellofemoral Syndrome

Neural Aspect to Patellofemoral Pain Syndrome - FEATURE

INTRODUCTION

Patellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal problems to exist. Recent investigations suggest that one of the possible causes of a lack of recovery could be an important hidden neural aspect.

This article discusses some research and its clinical implications with some suggestions on how to treat the problem from a manual therapy perspective.

Neural Involvement in Patients

BIOPSIES TAKEN FROM PEOPLE WITH PFPS SHOW THAT:

  • nerve ingrowth occurs in the area of the patients' pain (lateral retinaculum)
  • nerve fibre types found were both myelinated and unmyelinated
  • some of the fibres contained substance P, indicating their possible role in pain production (substance P can indicate the presence of polymodal C nociceptors)
  • S-100 was detected. This substance marks myelinated nerve fibres, indicating that the neo-hyper-innervation may also contain proprioceptive or motor aspects
  • The VGEF (vascular endothelial growth factor) was also present. This substance acts as a stimulus for neovascularisation in response to ischaemia
  • VGEF was also found in the axons of perineurium
  • Patients with more severe pain showed more VGEF in their lateral retinaculum

Figure 1. Substance P labelled nerve fibres in the lateral retinaculum of patients with patellofemoral pain syndrome (From Sanchis-Alfonso et al 2003, Acta Orthopaedica Scandinavica).


Figure 1. Substance P labelled Nerve Fibres
Figure 2.

The microscopic changes in the blood vessels in the area of pain were consistent with ischaemia eg. obliterated blood vessel lumina and foci of infarctions. It appears from this that the key mechanisms are excessive pressure and ischaemia to produce new neural and vascular tissue growth.

Figure 2. Process that may cause neural and vascular components to patellofemoral pain syndrome. Excessive pressure on the lateral knee structures, stimulation of substances that produce growth of new nerves and blood vessels (myelinated and unmyelinated).

CLINICAL APPLICATION


Figure 3. Medial Glides or Lateral StretchesAs there may be a neural element to some people's PFPS, it may be useful to perform a range of techniques that are directed at the neural tissues, either from a diagnostic or treatment point of view. Clearly local hands-on techniques may be useful but other techniques that target the neural tissues may also be applied. These involve the femoral nerve.

Figure 3. Technique of medial glides or lateral stretches to the lateral knee tissues. The aim is to reduce pressure on the lateral knee structures and mobilise the local nerves at the same time. The patient is positioned in the femoral slump position and the quadriceps muscle is stretched whilst the patella is moved medially, making this a neuromyofascial stretch technique (From Shacklock 2005).

IMPORTANT — since, in the flexed position, the lateral part of the patellofemoral joint line is very narrow, it is important to be sure that the patella is what is being moved. If the heel of the therapist's hand is positioned too laterally, it will only apply pressure to the lateral condyle, thus not producing a mobilising effect on the lateral joint structures.

The knee can be positioned in any amount of flexion/extension, depending on what is relevant to the patient. Some patients' symptoms occur in specific ranges of motion and the technique may emulate this whilst the neural tissues are positioned neurodynamically.

The medial innervation of the patellofemoral joint comes from the saphenous nerve. The nerve continues from the femoral nerve through the adductor canal where it can become compressed and may refer pain into the medial knee area (Morganti et al 2002).

The nerve can be mobilised with a number of techniques, including the saphenous neurodynamic test (Figure 4).

Figure 4. Saphenous neurodynamic test — involves hip extension, knee extension (since the nerve passes posterior to the knee axis of rotation) and, if necessary, plantarflexion / eversion of the ankle. This latter movement is based on the fact that a significant part of the nerve passes along the anteromedial surface of the ankle (From Shacklock 2005).


Figure 4. Saphenous N. Test
Figure 5. (5 A) Proximal Slider
Figure 6. (6 B) Distal Slider

Figure 5 and 6. Technique for sliding the femoral nerve through the adductor canal which may impact on anterior knee pain, particularly along the medial aspect. (5 A) — Proximal slider, hip extension/knee extension. (6 B) — Distal slider, hip flexion/knee flexion.

SUMMARY

Biological evidence exists that patellofemoral pain syndrome may contain a neural element. New nerve tissue has been detected in patients with the problem at the location of their pain. Mechanical techniques for a neural component can be performed and these are presented. They consist of:

  • mobilisation of the neural tissues at the same time as the lateral patellofemoral structures
  • saphenous neurodynamic test
  • proximal and distal sliders for the femoral/saphenous nerve tract.

REFERENCES

Morganti C, McFarland E, Cosgarea A 2002 Saphenous neuritis: a poorly understood cause of medial knee pain. Journal of the American Academy of Orthopedic Surgery 10(2):130-137

Sanchis-Alfonso V, Roselló-Sastre 2003 Anterior knee pain in the young patient - what causes the pain? Neural model. Acta Orthopaedica Scandinavica 74 (6): 697-703

Shacklock M 2005 Clinical Neurodynamics: a new system of musculoskeletal treatment. Elsevier, Oxford.

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