Background:
Approximately 90% of the population have a limb length discrepancy (LLD) of < 1.0cm, and a majority of these patients are asymptomatic. However, greater degrees of LLD can result in an increased likelihood of symptoms and complications. Current research supports discrepancies greater than 2.0cm to be clinically significant and require treatment. Symptoms may include pain involving the back, hip or knee, as well as gait abnormalities. Complications may include functional scoliosis and early osteoarthritis. Furthermore, LLD can be caused by a multitude of pathologies, and it may be challenging to determine the exact etiology during the initial presentation. The significant impact of LLD on patient outcomes, coupled with the numerous differentials, makes the approach to a patient presenting with LLD an important yet challenging one. We present this unique case of a vascular malformation with concomitant osteochondroma causing LLD in a young adult.
Objectives:
To report an unusual case of LLD in a young adult secondary to a deep intra-articular slow-flow venous malformation, with a concomitant osteochondroma; and to highlight diagnostic challenges when such lesions mimic common musculoskeletal conditions.
Study Design:
Single-case, retrospective report.
Results:
A 19-year-old male military soldier presented with intermittent atraumatic mechanical right anterior knee pain over several years. Examination revealed a 2.0 cm true shortening of the right lower limb (anterior superior iliac spine to medial malleolus). Pain was provoked by single-leg dynamic manoeuvres such as hop and half-squat. Clarke’s test was positive, suggesting a patella-femoral joint disorder. Galeazzi’s test was positive, suggesting femoral shortening as the cause for the LLD. Examination was otherwise unremarkable.
Long-leg standing radiographs confirmed the LLD and identified a contralateral proximal tibial osteochondroma without gross deformity. The preliminary diagnosis was patellofemoral pain syndrome (PFPS) attributed to mechanical overload from LLD. The LLD’s cause was not apparent at the initial consultation. Management comprised activity modification, physiotherapy, and orthotics.
Persistent symptoms after six months prompted further evaluation with a magnetic resonance imaging (MRI) of the right knee. MRI demonstrated dilated, tortuous vessels arising from the vastus medialis and extending into the prefemoral region, Hoffa’s fat pad, and femoral trochlea. Lesions were intermediate on T1 and hyperintense on T2, consistent with a slow-flow venous malformation; no arterial flow voids were present. Diagnostic catheter angiography confirmed the lesion, followed by catheter-directed embolisation using a cyanoacrylate adhesive. The procedure was uneventful. At 1-month follow-up, the patient reported marked pain reduction and functional improvement.
Conclusion:
Deep venous malformations may present beyond childhood and can mimic common entities such as patellofemoral pain syndrome, particularly when cutaneous stigmata are absent. Physicians should maintain a broad differential list when evaluating LLD, particularly in patients with persistent symptoms unresponsive to conservative management. Persistent focal joint pain with LLD warrants advanced imaging to exclude uncommon but treatable causes.
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