Os Peroneum and Os Peroneum Syndrome

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The os peroneum is found within the peroneus longus in 26% of feet.[1] They are usually located plantar to the cuboid, lateral to the calcaneus, or at the calcaneocuboid joint.[2] It is a factor in the development of peroneus longus stenosing tenosynovitis.[3]

Pathophysiology

Individuals with an os peroneum, especially those with hypertrophy of the peroneal tubercle, are predisposed to developing peroneus longus stenosing tenosynovitis in the cuboid tunnel.

Clinical Features

Patients complain of lateral ankle and/or foot pain.

Physical exam shows tenderness over the lateral plantar cuboid or at the calcaneocuboid joint. There may be thickening and tenderness of the peroneus longus tendons and peroneus brevis tendon sheath. Pain is exacerbated with the heel-rise phase of gait. Pain is also exacerbated by resisted plantarflexion of the first ray (first metatarsal and two phalanges of the great toe). The varus inversion stress test may provoke pain and this is performed by putting the foot in an inverted, supinated, and adducted position. Forced foot eversion may also cause pain.[2]

Investigations

Standard plain films show the Os peroneum (AP, lateral, mortise of the ankle, and AP and oblique of the foot). Also look for fracture, diastasis of multipartite Os peroneum, callus formation, proximal migration of the Os peroneum.[2]

Take care in not mistaking it for:[4]

  • os vesalianum pedis
  • os cuboideum secundarium
  • apophysis of the 5th metatarsal
  • avulsion fracture (pseudo-Jones fracture)

Treatment

First line treatments are rest, ice, and NSAIDs.

In severe cases immobilisation of the limb may be required.

The patient should also have a graded exercise programme.

References

  1. โ†‘ Peterson JJ, Bancroft LW. Os peroneal fracture with associated peroneus longus tendinopathy. AJR Am J Roentgenol. 2001 Jul;177(1):257-8. doi: 10.2214/ajr.177.1.1770257a. PMID: 11418450.
  2. โ†‘ 2.0 2.1 2.2 Sobel M, Pavlov H, Geppert MJ, Thompson FM, DiCarlo EF, Davis WH. Painful os peroneum syndrome: a spectrum of conditions responsible for plantar lateral foot pain. Foot Ankle Int. 1994 Mar;15(3):112-24. doi: 10.1177/107110079401500306. PMID: 7951939.
  3. โ†‘ Clarke HD, Kitaoka HB, Ehman RL. Peroneal tendon injuries. Foot Ankle Int. 1998 May;19(5):280-8. doi: 10.1177/107110079801900503. PMID: 9622417.
  4. โ†‘ Gaillard, F., Baba, Y. Os peroneum. Reference article, Radiopaedia.org. (accessed on 07 Mar 2022) https://doi.org/10.53347/rID-7648

Literature Review