Effect of the presence of cysts in the hip joint on hip arthroscopy

Abstract

Objectives: The aim of this study was to investigate whether the presence and size of fibrous cysts affected postoperative results in patients undergoing hip arthroscopy.

Patients and methods: Between January 2010 and December 2019, a total of 261 patients (138 males, 123 females; mean age: 39.5±11.9 years; range, 18 to 66 years) who underwent hip arthroscopy with the diagnosis of cam-pincer-mixed-type femoroacetabular impingement (FAI) and labral pathologies were retrospectively analyzed. The study groups (impingements and labral pathologies) and the presence of cyst (or cyst size: <5 mm, 5-8 mm, >8 mm) were used as the fixed effects, and the analysis was adjusted for baseline age, sex, and preoperative scores. Pre- and postoperative modified Harris Hip Score (mHHS) and Visual Analog Scale (VAS) scores that were applied to all patients were used as an indication of clinical results.

Results: The mean preoperative mHHS score of the patients with a cyst was significantly lower compared to the patients without a cyst (56.8±12.3 vs. 60.3±12.7, p=0.026). The mean change in the mHHS score and the mean percentage change in VAS score were significantly higher in the patients with a cyst compared to the patients without a cyst (mHHS score: 28.1±14.0 vs. 22.5±14.1, p=0.002; VAS score: 61.9±30.2 vs. 52.6±47.4, p=0.038). The increase in mHHS score over time for patients with a cyst was significantly higher than the patients without cysts in the pincer group (38.1±11.1 vs. 19.3±13.5, p<0.001). The patients with a cyst size of >8 mm had a significantly higher increase in the mHHS scores compared to the patients with a cyst size of <5 mm (29.5±12.9 vs. 23.5±13.8, p=0.043).

Conclusion: Subchondral cysts in the femoral head and neck junction accompanied cam-type and mixed-type FAI, while subchondral cysts in the acetabulum accompanied pincer-type impingement. In all groups, the mean increase in mHHS scores and the mean decrease in VAS scores were higher in patients with subchondral cysts than in patients without cysts. In patients with subchondral cysts, if the lesion causing FAI is treated arthroscopically, it can positively affect the functional results.

Figure 1. Magnetic resonance imaging of a left hip showing a subchondral cyst in the femoral head neck junction (arrows). (a) Coronal T1-weighted sequence, (b) coronal T1-weighted sequence, (c) axial T1-weighted sequence.

Figure 2. Magnetic resonance imaging of a right hip are showing subchondral cyst in the acetabular bone (arrows). (a) Coronal T2-weighted sequence, (b) Coronal T1-weighted sequence, (c) Sagittal T2-weighted sequence.

Figure 3. (a) Comparison of mean change of the mHHS scores in patients with and without a cyst across study groups. (b) Comparison of percentage mean change of VAS scores in patients with and without a cyst across study groups. Error bars represent 95% confidence interval of the mean.
mHHS: Modified Harris Hip Score; VAS: Visual Analog Scale.