Purpose

To evaluate short-term clinical and radiological outcomes of patients treated arthroscopically with CarGel for acetabular chondral defects in conjunction with microfracture (MF) compared to lesions treated with MF alone.

Methods and Materials

Patients who underwent hip arthroscopy and had MF +/- CarGel between 2012 and 2016 with a minimum clinicoradiological follow-up of 2 years were included. Intraoperative details and postoperative complications were analysed. Patients answered self-reported questionnaires, including the international Hip Outcome Tool (iHOT-33), Hip Outcome Score (HOS) pre-operatively and at 6 months, 1 year, and annually thereafter. Serial plain radiographs were assessed by two blinded observers independently for measurement of joint space and osteoarthritis grading utilizing the Kellgren-Lawrence scale. The number of failures, defined as a conversion to total hip arthroplasty (THA), was identified in both groups and correlated with the cartilage defect size at the time of surgery

Results

86 patients (53 Cargel, 33 MF) were evaluated with a mean age of 38.3 years at the time of the surgery. The average follow-up was 36 months. There were no statistically significant differences in iHOT-33 scores between the groups (p=0.85). 30% of MF cases progressed to THA while only 5% of Cargel cases did (p=0.0027). The mean defect size in the failure groups was significantly higher in the Cargel group compared to the MF group (8.8 cm² and 3.5cm², respectively; p=0.0002). Mean joint space reduction was 1.41mm and 0.21mm in the MF and Cargel groups, respectively, (p < 0.0001) denoting a significant decrease in the rate of progression to hip osteoarthritis in the CarGel group.

Conclusion

Arthroscopic treatment of chondral acetabular defects with CarGel demonstrated a significant decrease in progression to hip osteoarthritis and conversion to THA compared to MF alone. Short-term results are promising in this population of patients and this single-step, arthroscopic, cartilage repair technique does not burn any bridges.

Introduction

Acetabular cartilage defects are considered a precursor for early hip osteoarthritis. Bone marrow stimulation (microfracture), the standard of care, is recognized to be an incomplete solution for cartilage damage. BST-CarGel® is an injectable chitosan-based scaffold that is mixed with fresh, autologous blood and injected into the site of microfracture (MF) to physically stabilize the clot and enhance cartilage repair. It has been previously applied in the knee, with statistically significant greater lesion filling and superior repair tissue quality compared with MF treatment alone.

Content

The purpose of this study was to evaluate short-term clinical and radiological outcomes of patients treated arthroscopically with BST-CarGel® for acetabular chondral defect in conjunction with MF compared to lesions treated with MF alone.

Methods: All patients who underwent hip arthroscopy and had MF +/- BST-CarGel® application for acetabular chondral defects between 2012 and 2016 with a minimum clinicoradiological follow-up of 2 years were included. Intraoperative details (lesion size, grade, labral repair/reconstruction, associated pathologies) and postoperative complications were analysed. All patients filled out self-reported questionnaires, including the international Hip Outcome Tool (iHOT-33), Hip Outcome Score–Activities of Daily Living (HOS-ADL), and Hip Outcome Score–Sports Profile (HOS-SP) before surgery and at 6 months, 1 year, and annually thereafter. Serial plain radiographs were assessed by 2 blinded observers independently for measurement of joint space and objective measurement of osteoarthritis utilizing the Kellgren-Lawrence grading. A survival analysis was performed to identify the number of failures, defined as a conversion to total hip arthroplasty (THA), in both the groups which was in turn correlated with the cartilage defect size at the time of surgery.

Results: Eighty-six patients (53 Cargel and 33 MF) were evaluated with a mean age of 38.3 years at the time of the surgery. The mean duration of follow-up was 36 months. There were no major adverse events in both groups. There were no statistically significant differences in iHOT-33 scores between the groups (p = 0.85). Survival analysis at 3 years showed that 30% of MF cases progressed to a total hip arthroplasty while only 5% of Cargel cases converted to THA (p= 0.0027). The mean defect size in the failure groups was significantly higher in the Cargel group compared to the MF group (8.8 cm² and 3.5cm², respectively; p = 0.0002). Mean joint space reduction over 3 years was 1.41 mm and 0.21mm in the MF and Cargel groups, respectively, (p < 0.0001) denoting a significant decrease in the rate of progression to hip osteoarthritis in the CarGel group.

Conclusions: Arthroscopic treatment of chondral acetabular defects with BST-CarGel demonstrated a significant decrease in the rate of progression to hip osteoarthritis and need for conversion to THA compared to MF as an isolated procedure. Short-term clinical results are promising in this difficult population of patients; this single-step, arthroscopic, cartilage repair technique does not burn any bridges and could prove to be a cost-effective option for the healthcare system.

Study Design: Retrospective cohort study (Level III evidence)

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