Background

Plicae are inward folds of the synovium of the knee and are frequently found in the human knee. They normally appear as thin, elastic and almost transparent structures. However, several causes such as trauma or excessive physical effort can lead to thickening, fibrosis and stiffness of the plicae. The occurrence of this pathological process in the medial plica results in anteromedial knee pain, defined as the medial plica syndrome of the knee. Treatment of medial plica syndrome is initially conservative. When conservative treatment fails, steroid injection of the plica or arthroscopy surgery can be considered. Currently, little is known about the long-term effects of steroid injection and arthroscopic surgery on pain symptoms in patients with medial plica syndrome.

Objective

To investigate the effect of injections and arthroscopic surgery in the treatment of patients diagnosed with medial plica syndrome of the knee.

Methods

This retrospective study included 92 knees of 77 patients, who were diagnosed with medial plica syndrome and received treatment with either ultrasound-guided injections, arthroscopic surgery, or both. A questionnaire was used to clarify long-term effects of both treatments. Patients were asked to report their level of pain 6 months after injection, or 12 months after surgery, and at the time of taking the questionnaire. The primary outcome was pain relief as a result of the treatment and this was graded as excellent, good, fair or poor. Secondary outcomes were duration of pain relief after treatment, arthroscopic findings and postoperative complications.

Results

After injection with a local anaesthetic and steroids (n = 50), a majority of knees had a temporary relief of pain; in 74% the effect lasted less than 6 months. A mid-term effect between 6 to 12 months was reported in 6%. A long-term effect of more than 12 months was reported in 20%. After arthroscopic excision (n = 78), 72% scored good or excellent at the follow-up, which ranged from 12 to 112 months. Residual scar tissue was reported in 14 % of the operated knees.

Conclusion

Ultrasound-guided injections reduce the number of surgeries since it occasionally provides a long-term effect on pain relief. Furthermore, using ultrasound-guided injections in the treatment of medial plica syndrome improves the diagnostic process and therefore ensures better postoperative results.