Working Diagnosis:
Right chronic distal myotendinous junction rectus femoris rupture

Treatment:
She was referred to orthopedics for evaluation for possible tendon repair. Due to the chronicity and location of rupture at the myotendinous junction, repair was initially deferred due to outcome unpredictability. The patient was referred to physical therapy to improve lower body strength and tissue mobility but there was minimal improvement in pain or weakness. She was referred back to Orthopedics, who performed a rectus femoris tendon repair with tenodesis to the vastus intermedius.

Outcome:
After 16 weeks of rehabilitation, pain and strength are improving and she has progressed to explosive movement training.

Author's Comments:
The rectus femoris is a commonly injured muscle, especially in a sport such as soccer. Being a two joint muscle, it both extends the knee and flexes the hip. Muscle tears and avulsion injuries from the origin at the anterior inferior iliac spine are somewhat common, but a distal myotendinous injury is rarer, especially in the chronic setting. Many chronic, palpable masses in the anterior thigh are frequently misinterpreted as a soft tissue tumor or sarcoma, and many are even biopsied. There are a few case reports of acute surgical intervention for distal myotendinous rupture, but no studies on chronic injury intervention.

Editor's Comments:
Because this patient is an adolescent, avulsion of the Anterior Inferior Iliac Spine (AIIS), the origin of rectus femoris, should be at the top of the differential diagnosis list. Unfortunately, in the radiographs, the AIIS is obscured by the pelvis shield. This highlights the importance of obtaining adequate radiographs and of communicating the indications for ordering radiographs to the technician and radiologist.

References:
Huri, G., et al. (2014). "A Unique Rectus Femoris Injury in an Adolescent Professional Soccer Player: A Case Report." JBJS Case Connect 4(4): e115.

Murphy, C. M., et al. (2017). "Rectus Femoris Tear Presenting as an Unusual Cause of a Subcutaneous Mass." JAMA Dermatol 153(9): 945-946.

Ormaza, A., et al. (2017). "Chronic Quadriceps Tendon Rupture After Total Knee Arthroplasty Augmented With Synthetic Mesh." Orthopedics 40(1): 38-42.

Pope, J. D. and M. P. Plexousakis (2018). Quadriceps Tendon Rupture. StatPearls. Treasure Island (FL), StatPearls Publishing

Shimba, L. G., et al. (2017). "Surgical treatment of rectus femoris injury in soccer playing athletes: report of two cases." Rev Bras Ortop. 52(6): 743-747. doi: 710.1016/j.rboe.2017.1001.1001. eCollection 2017 Nov-Dec.

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