In this study, we found that hip arthroscopy had good clinical outcomes for revision surgery of SC. The VAS, mHHS and iHOT-12 improved significantly at final follow-up. The mean mHHS improved from 60.6 ± 17.3 to 83.8 ± 16.6 at final follow-up. The mean iHOT-12 improved from 43.8 ± 13.7 to 80.6 ± 19.7 and VAS improved from 3.1 ± 1.7 to 0.6 ± 1.8 at final follow-up. Two patients had recurrence of SC 1 year and 4 years after revision hip arthroscopy.
Several studies have proved that the arthroscopic approach had good clinical outcomes for SC of hip.[1, 3–5, 8, 14, 19] SC tends to recur and recurrence rate was reported from 7.1–38.8% after arthroscopic removal of loose bodies and synovectomy.[1, 10, 14] The recurrence rate in our hospital was 6.8%, which was similar to what Darren et al. reported. Boyer and Dorfmann evaluated outcomes in 69 patients treated with arthroscopy alone, of whom 51 required no further treatment and 18 required further arthroscopies. Of these 18 patients, eight had an excellent outcome, nine had a good outcome, and the treatment failed in one. Lee et al. reported recurrence in 4 of 24 patients who underwent hip arthroscopy for SC and these 4 patients underwent revision arthroscopy. SC recurred again in 1 of the 4 cases and a third surgery was performed. Ferro et al. reported 1 patients who underwent two revision surgeries after primary hip arthroscopy for SC and finally underwent total hip replacement 4 years after the initial hip arthroscopy. Zhang et al. reported 2 patients underwent revision arthroscopy because of adhesions within the hip or recurrent SC. Several revision hip arthroscopies for SC had been reported. However, the clinical outcomes of revision arthroscopy were quite different and current studies did not have detailed clinical follow-up. We evaluated consecutive patients who underwent revision hip arthroscopy for SC in our hospital and proved that that hip arthroscopy had good clinical outcomes for revision surgery of SC. The mean time between primary surgery and revision surgery was 30.8 months (range, 4–96 months) in this study. Lee et al. reported the average period between the first surgery and recurrence was 3.2 years (range, 0.8–3.8 years). Boyer et al. reported the mean time between the first and second arthroscopies was three years. The time between primary surgery and revision surgery of the three studies was similar.
According to the current researches, the main causes for revision arthroscopy were recurrent SC and adhesion. In this study, 7 patients underwent revision surgery because of recurrent SC, 2 patients underwent revision surgery because of adhesion and one because of remaining loose bodies. One of the two patients with adhesion had recurrent SC and we thought recurrent SC may be the reason of adhesion. One patient did not achieve good clinical results. Her mHHS improved from 20 preoperatively to 43 postoperatively and iHOT-12 improved from 18 preoperatively to 32 postoperatively. VAS improved from 7 to 5. Recurrence of SC was found 4 years after revision arthroscopy. At final follow-up, range of motion of this patient improved, but the symptoms did not improve much. Recurrence of SC was found in 2 patients 1 year and 4 years after revision hip arthroscopy, respectively. Lee et al.  reported that the symptomatic SC recurred in 4 of 24 cases who underwent hip arthroscopy and symptomatic disease recurred again in 1 of the 4 cases, and thus, a third surgery was performed. The condition of the patient who underwent the third surgery was exacerbated because of adhesions resulting from extensive intrajoint synovectomy, and the range of motion of the hip joint was decreased after surgery compared with the patient’s condition before surgery. Ferro et al. reported 1 patients who underwent two revision surgeries for SC and finally underwent total hip replacement 4 years after the initial hip arthroscopy. In this study, the two patients who had recurrence of SC after revision arthroscopy did not accept third surgery. SC tends to recur whether after primary surgery or revision surgery. It should be mentioned that one patient in this study underwent hip arthroscopy for SC as primary surgery and underwent open surgery for recurrent SC as the second surgery in another hospital. This patient underwent hip arthroscopy for SC as the third surgery in our hospital. This patient had serious recurrence after second open surgery and the SC expanded along the incision and some even grew to obturator externus muscle, which made the third arthroscopy surgery so difficult that it was impossible to remove SC completely (Fig. 2). This patient was satisfied with the outcomes of third arthroscopy surgery. At one-year follow-up, this patient had no obvious discomfort and could walk and live normally. He felt a little discomfort only when the hip flexion angle was more than 110 degrees.
It should be noticed that 4 in 8 patients who underwent revision arthroscopy had combined FAI. Such a high rate of combined FAI may be related to repeated stimulation of SC. The association between FAI and SC has been reported previously by Padhy et al. in 2009, who described a case of FAI accompanied by SC. Abolghasemian et al. proposed that SC can induce changes compatible with typical cam-type FAI, and that this can represent another mechanism leading to hip osteoarthritis in patients with SC. The presence of unilateral cam-type impingement can be a clue to a possible diagnosis of underlying SC.
This study had several limitations. First, the sample size of this study was small. However, the patients who underwent revision arthroscopy for SC was scarce. Second, the time of follow-up ranged from 12 months to 120 months. One patient had a relatively short follow-up.
In conclusion, hip arthroscopy had good clinical outcomes for revision surgery of SC.