This month’s radiology case involved a 20-year-old female national level football player. She presented with a three-month history of left-side lower back pain, which had come on insidiously.

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On examination, she had tenderness over the lower lumbar spine in the midline, and lumbar extension was painful.

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As the player was not improving, an x-ray series of the lumbar spine was arranged. The coned AP image of the lower lumbar spine showed a transitional L5 vertebrae which was sacralised on the left. The transverse process on the right was normal.

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A subsequent MRI further defined a pseudo articulation with the left sacral ala, with bone marrow oedema on either side of the pseudo arthrosis.

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The player was successfully managed with a short period of rest, followed by a return to training and match play. She has continued to experience low-grade, episodic lumbar pain, which has largely been controlled with a stretching and core stability programme.

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Bertolotti's syndrome is a relatively uncommon cause of lower back pain that occurs due to sacralisation of the lowest lumbar vertebral body, or lumbarisation of the uppermost sacral segment.

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It is a congenital condition that does not usually become symptomatic until players enter their twenties.

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Commonly reported symptoms are lower back and buttock pain, while radicular symptoms can also occur. In most cases, the transitional vertebra can be seen on AP x-rays as a "spatulated" transverse process. This can be associated with increased signal on T2 MRI sequences. The pseudo articulation can lead to restricted or altered motion at the lumbo-sacral articulation, which can either cause pain directly, or create stress at the L4 disc level.