Beyond the patella: Treatment of cam femoroacetabular impingement syndrome improves anterior knee pain

Objectives

This study aimed to investigate if there is a relationship between cam femoroacetabular impingement syndrome (cam-FAIS) and chronic anterior knee pain (AKP).

Methods

This is a pilot retrospective review of 12 AKP patients with no structural anomalies in the patellofemoral joint and no skeletal malalignment in the lower limbs. All the patients were resistant to proper conservative treatment for AKP (AKP-R). Subsequently, these patients developed pain in the ipsilateral hip several months later, and upon evaluation, were diagnosed with cam-FAIS. Arthroscopic femoral osteoplasty and labral repair were performed and clinical follow-up of hip and knee pain and function (Kujala Score and Non-arthritic Hip Score -NAHS-) was carried out.

Results

All the patients showed improvement in the knee and hip pain scores with a statistically significant clinical difference in all of them at 69 months follow up (range: 18 to 115) except one patient without improvement in the groin VAS score post-operatively. Visual analogical scale (VAS) of knee pain improved from 6.3 (range: 5 to 8) to a postoperative 0.5 (range: 0 to 3.5), (p ​< ​0.001). The VAS of groin pain improved from 4.4 (range: 2 to 8) to a postoperative 0.9 (range: 0 to 3), (p ​< ​0.001). NAHS improved from a preoperative 67.9 (range: 28.7 to 100) to a postoperative 88 (range: 70 to 100), (p ​< ​0.015) and knee Kujala's score improved from a preoperative 48.7 (range: 22 to 71) to a postoperative 96 (range: 91 to 100), (p ​< ​0.001).

Conclusion

This study's principal finding suggests an association between cam-FAIS and AKP-R in young patients who exhibit normal knee imaging and lower limbs skeletal alignment. Addressing cam-FAIS in these cases leads to resolution of both groin and knee pain, resulting in improved functional outcomes for both joints.

Study design

Retrospective cohort series with a single contemporaneous long-term follow-up.

Level of Evidence

IV.