Prevalence of MRI changes in Deland (2005)
- Tibialis posterior tendon 94%
- Spring ligament 87%
- Interosseous talocalcaneal ligament 48%
- Anterior superficial deltoid ligament 31%
- Plantar fascia 26%
- Posterior superficial deltoid ligament 19%
- Tarsometatarsal ligaments 19%
- Deep deltoid ligament 13%
- Naviculocuneiform ligament 13%
- Long/short plantar ligaments 6%
Degenerative change
Mosier et al (1998) showed that the pathology of tibialis posterior tendonopathy is much the same as that of other tendons such as the Achilles tendon and rotator cuff. They compared 15 tendons with surgically proven tendonopathy with 15 cadaver controls. There was thickening of the surgical cases, but no loss of continuity. The alignment of collagen bundles was lost, there was mucin deposition, myxoid degeneration, hypercellularity and neovascularisation. Fowble et al (2006) confirmed these findings and emphasised the presence of neovascularisation. These are similar findings to those in other degenerative soft tissue conditions such as Achilles tendonopathy and plantar fasiopathy. Deland (2005) showed that MRI changes suggestive of degenerative change and tears are present not only in the tibialis posterior tendon, but in the spring, deltoid and interosseous talocalcaneal ligaments.
Tendon circulation
Zone of relative ischaemia and possible attrition in tibialis posterior tendon (green).
Insertional tendonopathy was present in six patients in Suneja's study (pink)
Frey et al (1990) identified a 14mm zone of relative ischaemia in the tendon between the medial malleolus and the navicular. This zone also has a sharp turn round the medial malleolus, so that Jahss (1982) suggested that this was an attritional rupture associated with stenosing tenovaginitis. Uchiyama (2006) showed that the flatfoot position increased the gliding resistance of the tendon and suggested that in a pre-existing flatfoot deformity this could contribute to the development of tendonopathy.
Insertional tendonopathy is well-recognised in the Achilles tendon and was described in the tibialis posterior tendon by Suneja (2006).
Some recent studies have examined evidence of autoimmune processes and abnormalities of collagen metabolism – this approach may yield important information in future but as yet no conclusive data have emerged.